My DIL is much the same. She was fine at beginning (that was approx 20 years ago) but once DIL and son became more solid she somehow changed. Also, when my husband passed away she somehow became more distant towards me. I think she feared I would become dependant on them both. I understand her mother told her to be careful in that I become too needy - if anything I am quite the reverse. I am a bugger to ask for help at the best of times in any event and I have always been that way unless of course absolutely necessary. I believe much of her negatively towards me does come from her own mother. So, some years back I gave up trying to ease our relationship, trying to be friends or mates with her. Pointless. So nowadays I just work around her and only when it is convenient for her and my son I get to see my grandchildren (who are priority). At times I will get a phone call from son saying I can visit as DIL is out for whatever reason so I will visit then. Of course she is fully aware and it does not bother her at all and it does not really bother me. Likewise she has never been to my home in the 20years - of course she is asthmatic and is allergic to cats so therefore she cannot visit in any event - which I would say suits us both fine. The times when we have had to spend time in same room we are very polite to each other, i suppose we both tolerate each other but It’s not really comfortable, but then my focus is a lot on grandchildren. I accepted long ago we would never be the best of friends - it happens! It’s a shame in many ways as would have been nice to have a DIL who could be your friend, and I am sure she feels same about me. It happens in all families I.e sisters don’t get on, brothers don’t get on, relationships between parents and child also are not always perfect either! I just make the best of what I got and enjoy.