AIBU to let my nephew stay with us in holidays?

Is there a dad on the scene @CollectingSeashells

I'm intrigued as to why your nephew is so agin going back to somewhere that, he says, no longer feels like home; to the extent, he has asked to stay with you, which house isn't 'home'.
I'd be encouraging him to talk to you, but offering the perspective that his mother, your sister, is a grown woman, not just 'Mum'.
Your nephew is an adult and, unless the partner is abusive, unkind etc, he'd benefit from accepting that, just as his life has moved on, what with uni etc, so has his Mum's.

Can you tell us a bit more about why your nephew doesn't want to be around his mum's partner? What's the problem?

has he given any meaningful explanation of why he doesn’t like this guy? If not then surely your sister should prioritise finding out.

It could be that he just hates the idea of his mum with anyone but if it’s something more worrying such as the way the BF treats his mum or him, then that needs discussing.

i think you’re doing the right thing but should have a discussion about what he plans to do after Uni.

I don’t really understand how you can say you understand your sisters side of things. She is being very selfish, even if she has waited for her partner to move in.

in no other situation would an adult be expected to just put up with sharing their home with a stranger against their will, yet children of parents who want to live with a new partner are supposed to deal with it and have no feelings about who they live with.

OP, do the right thing by your nephew. Your sister is being horrible.

Absolutely he should come to you. Please tell him that you’d like that, assuming you do of course.
He can fix his relationship with his mum at his own pace but stalling when he’s directly asked for your help seems unkind.
His needs trump your sisters currently I would say.

I don't think you are unreasonable for letting him stay with you but I think it might be beneficial trying to encourage him to keep a friendly communication with his mum and for you to as well, despite the disagreement. Not saying the new partner is awful or abusive, but there must be something amiss for a 20 year old not to want to go home from uni because of a parent's new partner. It's normal for people with abusive traits to separate partners from their family and it's interesting it took her so long to get him to move in and only happened once the son was at uni (I'm assuming). Again, not accusing, just best to keep communication open and friendly for the future.

How is she being awful? Her sons are adults who live away and she has a partner. That’s allowed! What is she supposed to do, put her partner out in the summer holidays?

I think he needs your support - but to see his mum is a grown woman who is allowed a partner. Some counselling perhaps to work through his feelings.
His mum has given him so much but now he's giving up on her.
Or if you let him stay apply the same rules his mum and partner have

He's an adult. It's not really anything to do with her.

If she cares so much then she'd move her partner out.

You sound like a lovely auntie.

Your sister is being awful to her son. Hes made his position and he's an adult. I would absolutely in this situation be siding with nephew and letting him stay. Awful that a lot of women put men before their children.

Your sister should be trying to talk to her son to find out what the problem is and be happy he can come to yours and focus on trying to work through the issues and be a supportive mother. She's the one facilitating the worsening relationship with her son.

Please support your nephew so he knows he's someone in his corner. The fact he has went home previously and now doesn't with this man there would raise red flags.

He's an adult, so it's between you and him. However I'd suggest to your sister that she takes her son out for food, days out etc because he does have to get to know her DP. Or have them over for tea. Come Christmas, you are possibly all going to be mixing. You also need house rules. If he's adult enough to make decisions on were he lives, he can do his own cooking/cleaning/washing. Are you going to be buying his food etc? It's got to be all said, upfront.

He is unlikely to go home just because you won’t have him.

my dc in similar circumstances did not want to go “home” to their dad and his new wife.

my dc largely stayed at their uni house.

If he's 20 he gets to decide where to stay. It's not up to your sister to tell him he can't stay with you.

I don’t understand what exactly she thinks you’re doing wrong? Facilitating his not going home? But he wasn’t going home anyway because he was staying at uni. Plus he is an adult.