AIBU to refuse to attend my nephew's birthday when my sister excluded my partner, then expected me to apologise?

[lavendersweetly]

Some details changed privacy reasons

I just need some perspective here please.

So, a few months ago, my sister texted me and told me that she was holding a 1st birthday party in May for my nephew, Reeson, and that she would love for me to be there, but that my partner and our stepdad weren't invited. For context, our stepdad has been in our lives for 15 years...
She said that she decided to make it a joint function with Reeson's nan (my brother-in-law's mother) at the last minute, and that there was "no room" for too many other guests. Mind you, she and BIL invited SEVERAL of their friends, but the only people on her side of the family that were invited to Reeson's birthday party was my parents and I.
I am not familiar with R's grandmother at all, and we have only ever made polite small talk if we've ever been at a function together. My BIL in law and I also do not have the greatest relationship, though I believed it was starting to improve until this happened.
Now, it also happened to be my anniversary with my DP in May anyway, so we had made plans well in advance of the invite. I politely and respectfully advised her that, whilst we had already made plans for our anniversary, I wouldn't feel comfortable attending the function without my partner in any case, but that I was grateful for the invite, and that I hoped they had a lovely day.
He is my life partner and as much a part of Reeson's life as I am, whether she sees it that way or not, so I would assume that she would have understood my position, however, clearly she didn't because she simply responded "Lol". I replied and asked her to clarify what she meant, but she did not.

As a result, we then didn't talk for several weeks. To be clear, she did not make any effort to contact me, to ask how my family and I are getting on, nothing whatsoever, just radio silence.
A mutual friend then intervened, and told us both that we were being childish, and that we just needed to talk and clear the air of any misunderstanding. I took the feedback on the chin and subsequently texted my sister on 3 separate occasions and I told her that I loved her and Reeson. I invited her round for a cuppa and a chat and to see if we could sort it out, but I did not receive any kind of reply for several weeks.
She then contacted me out of the blue in August and said that she believes we could rectify the situation, but that she was hoping I "had something to say". In retrospect, it's easy to see now that she was waiting for me to profusely apologise for refusing to attend without DP...
I replied and told her that I didn't have much to say as I had already had time to process the event and move on from it, but that I do believe our wires had been crossed and that there was a communication breakdown. Again, I invited her and Reeson to my home for a chat because I was off work, but it seemed that my response was still not satisfactory enough, because she simply responded that she wasn't prepared to move past the issue, and that was that.
I have since texted my brother-in-law to ask how they're all getting on. He received the message but did not respond.
My sister and I have not talked since.

I'm really hurt that she has made no effort to contact me whatsoever. She hasn't once asked about how myself and my family are getting on because she clearly doesn't care, and I'm not sure if I do anymore.
The irony of it all is that she hasn't asked me ONCE how my son is doing either 😂

You do know you can attend things without your partner and that’s perfectly normal don’t you?

It seems like a giant storm in a teacup over a baby’s birthday party. I mean, aren’t they usually a matter of some tea and cake with grandparents, if local?

She can but why should she. It’s a family event and DP is family to OP, as is the stepfather.

Your mutual friend was, and is correct. Very childish.

Not too sure how to answer your pole, but YANBU to not attend, as you already had plans anyway. YWBU to make it about her not inviting your partner, it wasn’t his birthday. YAbothU for not apologising to eachother for acting like children.

Because it wasn’t their kid, and wasn’t their party.

You are both batshit. If birthday party was important for you, you wouldn't have made plans for your anniversary. Surely, a one-year-olds birthday date is not a surprise to either of you. Personally, I checked with my cousin which weekend they were planning to celebrate their son's birthday so that I could arrange my travel plans accordingly.
But since you did have other plans, what possessed you to launch in a lengthy explanation about you attending with your partner only? Neither of you were free to attend! A simple "I am sorry, I won't be able to make it. I'll drop a gift during the week" is plenty.
Your sister is ridiculous to make such a big drama over this month's later.
Both of you completely blew it out of proportion.

Quite aware, yes. We're not joint at the hip, but on this occasion I didn't want to attend without him, so, I chose not to :)

your sister is not obliged to invite your partner and partner's dad to her child's birthday party

you are not obliged to accept her invitation (but could have given a better polite excuse and not mention your partner)

she is being petty to expect a big apology

You are both being unReesonable.

Edits:

• The party was very last minute and I wrote this in my post. She had expressed on several occasions that she was never bothered about having a party for Reeson, so there was no way for us to know that this was going to happen, hence, having made plans for our anniversary MONTHS in advance of this....
• My response to her initial invite wasn't lengthy at all and my post doesn't say that at all either. I simply told her that I would not be attending and why, thanked her for the invite and that was it 😂My post is lengthy here because that's the point of this AIBU forum, correct?
• I agree that she is ridiculous 😅

You are all ridiculous.

@parietal it’s OP stepdad I believe not her partners dad

😂😂😂😂

Presumably someone (your sister or her husband maybe) don't particularly care for your partners company?

How did her not inviting your step father play out with your mum? Have they fallen out too?

Mum is absolutely mortified and she also didn't attend for this reason, but no, my sister hasn't fallen out with her, only me

Surely nobody actually called real life child Reeson?

Actually I think you’re wrong, she didn’t have space so she didn’t invite your partner. To a first birthday, big deal. Mine would have been delighted with that arrangement

It sounds like you (and possibly your sister) are ready to ramp yourself up to an Eastenders level of drama on any old pretext. Perhaps you've always been like this in your relationship, and it has served some sort of psychological need. But now it is impacting on children so you should make the effort to move past the patterns of your own childhood and adolescence.

I’m assuming that’s one of the changed details. Or hoping so for the little ones sake.

Shes nuts OP. Ignore, ignore, ignore.

Fair play there 😂

I'd be still laughing if someone told me they wouldn't feel comfortable attending their nephew's first birthday party without their partner.

It sounds like a bad soap opera.

could your mum have a chat with her maybe?

You weren’t going to attend regardless due to having other plans, so why even mention your partner not being invited when you declined? It was entirely irrelevant, as you weren’t going to go anyway.

@lavendersweetly how long have you been with DP?

And you didn’t ’refuse to attend’, you just had other plans. So much drama.