I interrupt MIL selfish monologues with yes I know, you told me this before.

Maybe they don't. In which case why would they be at his graduation dinner?

YANBU at all, OP. I imagine that those who have not suffered similarly over many many years cannot comprehend how infuriating it is. You were right to interject, it may make MIL think a little - though she won't change - and more importantly, it let your son know that you care about his feelings and want him to feel good on his big day.

My husband (who is generally a lovely man) has a tendency to do this. Any story I (or anyone) tells he interrupts to tell his own barely relevant anecdote. He's autistic and I think it's his way of relating to people. Any chance there could be similar issues with MIL?

I do pull him up on it every time!

Have you tried bringing the conversation back to a more appropriate topic?

or, when you are just the two of you, talk to her about it. Say you have noticed that she monologues and could she try to be aware of it next time so that other people can talk instead?

Mil used to tell us about her toilet habits. I used to hurry off to the loo every time. Grim I tell you. Incessant chat about her poo schedule...

MIL does this. We were at her place because her sister was visiting (DH's Aunt) and our DD was learning to drive at the time. DD says 'oh I've started driving lessons grandma' so this clearly meant a 5 minute monologue about how long grandma had taken to learn to drive, what car she learnt in, what her driving instructor said, how many tests she did, what the examiner said...yawn...never once asking DD how her experience was...

After a few minutes, DH's Aunt says 'enough about you, how about asking your granddaughter how her driving is going' with a wonderful eyeroll! hehe....i did laugh out loud. MIL still does it though; she just loves the sound of her own voice. 🙄Until DH tells her to stop being so self-absorbed...she never takes offence though.

YANBU to stop her, my DF and a few friends do this. Often a quick "you told me before " moves the conversation on to a previously unheard monologue, which is better than a repeat.
I agree it'd an age thing too. My DM kept everything secret, until she hit her mid 70s and suddenly a whole lifetime of stories is coming out in monologue form.

@TheRubyPoet
There are all types of people and you, for instance, appear to be the type of person who feels that everyone, regardless of how they are as a person, should behave according to your “unwritten rules”.
So maybe you believe that at all social gatherings conversation and attention should be allocated in specific ways, according to the reason for the gathering. So if celebrating a birthday, the birthday person should get more attention, idem for a graduation etc.
Not all families do this, and that is perfectly normal too because some people do not want that attention or responsibility to carry the conversation, and others, maybe like your MIL, have this as part of their character, not a conscious decision to override the discussion.
My family would be perfectly ok with letting a member of the family be as they are, and no-one would feel the need to make them feel bed about talking about themselves. If someone wanted to contribute more to the conversation we would expect them to speak up themselves, not try and shut someone else down.
As an aside, we are a ND family, and bringing the conversation back to personal anecdotes is a very common way of communicating within the neurodiverse community.

Yabu to go about it that way and let it come to a head in that manner. Yes, she might be spoiling the night but there's no need to make that the night that you pick to lock horns.

I'd have smoothed over it at every point because its DCs night and not the time or place for letting things get out of hand and spoiling things.

I'd have said stuff like "yes, that was fantastic! I bet that now DC has graduated he has lots of plans. DC, let's hear about [the travelling you have planned/new job] X".

What a rude post.

The MILs who justify this behaviour are out in force.

I don't think saying you've told me this before is the way forward.

I'd focus on letting her know you hadn't stopped talking or telling her someone else has been waiting to speak for a while.

My MIL has always been like this but it's getting worse. She's really not interested in anyone else anymore and can only relate things to herself. My littlest finishes primary next week and I'm already bracing myself for the fact that when she comes over we will all hear the same stories again and again as she makes it all about her. My granny got to be the same and also went deaf so she couldn't participate in conversations, only monologues about herself - but I loved her and didn't mind. With MIL, who I also love, it has a more competitive edge - she always wants to cast herself as the best and most important person in a situation.

The only way I've found to deflect the same unbearable stories from coming out again is to ask her other questions - also worked with my granny while she could still hear. I can sometimes deflect her onto something more interesting - usually about family history, and because she doesn't have a prepared story about it, we get something more honest and less full of self-aggrandisement.

I don't know why it's a trait that's intensifying; it's not an age thing - my mum is older and always very keen to hear about everyone else's life! But MIL seems very anxious when the conversation moves to a subject that isn't her.

YABU. Her rambling might be annoying, but it's harmless, and is only when you are with her. You, on the other hand, sound rude, intolerant, and a bully.

Then they shouldn't have been at a meal to celebrate it, should they?

My father does this. He's very out of touch with real life so his stories are very boring and we've heard them all before. He doesn't care that nobody is interested and we've heard it all before, he just likes to hear his own voice. He's 82 so this has been going on a long time and we now cope with it by ignoring him and just starting our own coversations while he drones on. Fortunately he doesn't have a very loud voice and because no-one wants to sit next to him he tends to be sat right at the end of any table so this is pretty easy to do. He either doesn't notice or doesn't care and just carries on regardless. Yes, we're probably rude but so is he.

MIL still kept talking anyway.

I bet son is probably just as used to it just like his dad is.

When my mum does this, I’ll usually finish the sentence or say yeah, you said that before. If she carries on, I just ask my daughter a question and start a new conversation. Hugely rude but I’m done pandering to her these days.

Could you stand up and say, right, I'm going to nip to the loo and when I get back I would love to hear more from the kids about what they want to do this summer hols! Anyone want a cuppa while I'm up?

I think you've got to just cut it off and change up the energy, leave the room, create a distraction, otherwise just stay away from it as much as possible, I used to feel like I'd been energetically mugged after spending time with FIL, and it was few and far between by design.

i agree with this BUT if it causes a scene then that's what the son will remember.
So I would leave the confrontation for another time.
Humour might be a better way to deal with it.

It was the son’s graduation dinner, the reason people were there.

MIL was the rude one.

YANBU - people like your MIL are infuriating. There have been so many threads on this subject recently so you’re not alone.

A relative of mine does this all the time. Most recently, I told her some news about something that’s significant to us as a family. She responded “that’s nice, did I tell you I lost 3lbs?” then proceeded to rattle off everything she’d eaten in the past week.

I’d advise you to have minimal contact from now on.

I really really struggle with my mum doing this.

it’s very difficult because if you make her aware she is doing it she becomes very upset, but it doesn’t seem to stop her.

she is 80.

my kids avoid spending time with her also as it’s often the same stories over and over again and they’ve heard them hundreds if not thousands of times now.

i feel obliged to go and see her/have her to stay but I do find it hard. If we do get a proper conversation going it doesn’t tend to last long before it lapses into a monologue again.

if anyone has advice I’d be interested.

You’re being rude, especially when you saw it upset her.

Maybe nobody cares about your kids graduation. See how that upsets you.

I don't mind it so much when people are just gathered and it's just another conversation. Boring, tedious and extremely trying but I'll put up with it.

But in OP's situation I'd've said something too - it's not the time for the usual suspects to drone on and on about themselves yet again.

Inside it annoys me but saying I have heard it before achieves nothing other than some territorial tug of war thing seems to be popular on here with MIL and DIL