She commented about relationship

[Hayles2]

I have only briefly met my partner’s sister twice. Last night she said on the phone if he was single she has a friend she could set him up with. She didn’t realise I could hear and he said he is very happy with me etc and then she ended the call after that. I found this quite hurtful, why would she even say that when he is with someone. Apparently she used to say that to him when he was married to his ex wife which the ex wife found offensive.

The sister set him up with someone else in the past who was a domestic abuser towards him so she doesn’t have good judgement. What is the best way to not let the behaviour bother me?

I don't know (presumably she didn't like his ex-wife and doesn't like the look of you on the two occasions you've met?), but I can't imagine being that bothered by the opinion of a partner's sibling you've met twice. How long have you been together?

He is an adult and it's totally ridiculous that she thinks she thinks she has the right to interfere in his relationships.

I don't think it's any reflection on you as a person. She probably wants to set him up with someone who would suit her life better - someone shes already friendly with.

However I think it's quite upsetting for you and if you are in a serious relationship with your partner it's going to make interaction with his family pretty uncomfortable for you if the vibe is that she thinks he should have chosen someone else.

Your DP should explain to dear sis that not only is he very happy with you but, if she can't respect the relationship, he will have to rethink their relationship.