DS' girlfriends dad

[FrenchiFanci]

I have 2 kids DS1 turned 18 in October, is in Y13 and studying for his A-Levels.
He has a girlfriend, she's 17, also in Y13, they've been together for about 7 months. They are both very intelligent (A/A*a predicted), lovely kids (compared to DS2 anyway who is definitely a bit more troublesome). They never cause hassle and keep themselves to themselves.

Yesterday DS went to work 10-4 in a local supermarket, his gf also works (sports coaching) the same times on a Sunday. Afterwards they both came back to ours at about 4.30. Went upstairs to his room, ordered pizza around 7.30 then she left at 9.30 to go home. I didn't check in on them they were quiet and seemed to be fine.

This morning I get a message from her dad (he's a single dad) having a go at me as they didn't study at all, and he knows because he checked her books and she admitted they played sims and watched a movie. He has said unless I make sure to check in on them studying she won't be allowed over anymore.
I haven't replied.
I told DS via message and he replied with "yeah he's a bit psycho gf says not to worry he will be over it by tomorrow".
I've left the message on read as I have no idea how to reply and I'm working from home.
Now he's tried to call twice and sent a follow up message saying this needs to be sorted, followed by another saying "it's because of your lax parenting that they are having sex in my house and that it's disgusting I allow it" (they are 17 and 18 I don't really care if they are having sex!!)
I'm totally lost on how to reply to this, they are good kids and she's a really lovely girl. We've never had her dad be like this before (an odd message when she's been home late but that's it)
AIBU to think this is concerning and be unsure how to reply or deal with this - any advice?

Block and don't engage? 🤷🏻‍♀️

Can't possibly imagine why on earth he's a single dad with an attitude like that. No need to get involved imo, I'd just let him rant away in his own head and ignore.

That’s an odd one!!
to be honest I’d probably just ignore, can’t reason with someone like that usually.

I think I would just ignore.

If he continues just say they are both nearly adults, so it's not really your problem.
Surely she can study at home when she's not with ds? Sounds like he's one of them people who just like to complain!

I'd ignore it.

I don’t think I’d dignify this arsehole with a reply, he’s obviously spoiling for a fight. But I would most definitely block him.

Ignore him.

He's sounds like a wanker.

Another vote for ignoring him.

He sounds like a nasty piece of work, tbh.

Ignore.
It's up to her if she studies, she's almost an adult.
I think I would keep welcoming her in your house, her home life sounds a bit stressful.

"Your concern is noted. She is welcome in our house at any time. If you chose to forbid it, it is your prerogative but I will not be entertaining any more comments on my parenting. Kind regards, FrenchiFanci".

You can’t rationalise with someone like him. He’s disgusted and allows it in his home yet it’s your fault? Hmm.

At 17/18 studying is definitely down to them.

Hmmm I wouldn’t ignore him.

For the girl’s sake if anything

I think he’s awful and he has gone on a rant

I think it’s dreadful talking about her sex life!

D you know where the mother is? I hope he didn’t torture her so much she left for good!

poor girl.

I like @Catza reply.

I think the sex thing is that OP allows it in her home rather than it happens in his home.

Her mother isn't English (I think she was Russian if I remember correctly), apparently she left when her daughter was 3 and hasn't returned!! I imagine things have to be pretty horrific to get up and leave your child!

Great reply!

Text him back "R U OK hun?" 😉

I'm not sure I would engage. He's clearly looking for a fight and trying hard to draw you into one. Don't engage. If he knows he can get a response out of you he will do it all the more. Leave it on read and just let him blow off steam to himself. If it's not drawing you in to a confrontation it will seem a waste of time to him.

Or U ON GLUE HUN?

I wouldn't engage with someone like that, it will just be a massive drama.

How the hell would he know whether she's having sex or not?

I agree with this. I think ignoring is not the best. This give a response, but makes it clear no further response will be forthcoming.

He sounds like an absolute horror of a man.

I wouldn't reply to him, but I'd certainly be having a chat with your son about his girlfriend's dad to find out a bit more about him and what your son thinks of his behaviour towards his daughter. It is insane to expect to enforce study time on 17-18 year olds, and even more so on a bloody Sunday afternoon. They're entitled to leisure time. And going on about them having sex at your house is just fucking creepy when they're aged 17 and 18. How does he even know? She doesn't even stay over, from the sound of it.

Do you know your son's girlfriend well enough to have a chat with her about it? (Not the sex stuff obviously, but the level of anger/control her father seems to put on her?)

It's not your fault if they are having sex in HIS house.

Reply "sorry you feel that way. I think they are both good sensible kids and so I don't check of they are studying at all times or not...they are allowed some down time. Its nothing to do with me what they do in your house and I won't be chaperoning them in mine."