Worried about DD and bf relationship

Interfering with other people’s relationships rarely does any good and may make her prickly and defensive. Remain polite and friendly so he has no excuse to cut you out of their lives. Perhaps he is totally different when they are alone? Without knowing the people concerned makes it hard to say what is best and even then is down to your character and his. Just don’t let him push your buttons like the partner of one family member did. Some years ago now and still a huge deliberate rift.

Does he openly pick fault with your family, or is it that he says things to your daughter about it?

I'd say the way he talks to her may just be habit. I'd take far more notice of how he behaves.

My SIL is always complaining and moaning. I've realised now that it's just his way of communicating.

He's a loving, affectionate husband and father, though. That's the important thing.

I'm not berating him, not to her anyway, I just needed someone else's opinion

Yes we are isolating, they living with us with their baby atm, I will tread carefully, just feel myself watching everything I say and every move in case he uses it against us

I would pick a very quiet time when you are alone with your daughter before bringing this up. Since we are all distancing from each other, how are you witnessing this? Does your daughter complain, or do you all live together?

Instead of berating him, let her know you are worried about how she is, and that she should be strong ,confident and happy in her relationship.

Nobody likes to hear bad things about someone they love, and she may get very defensive and hurt. Tread carefully.

Are you not isolating? Surely, we just keep in touch at this time. Support your daughter by all means - but it's their problem to sort out - if there is a problem.