As the daughter in a marriage, will give my very one sided opinion.
You may not do this at all, or be totally unaware if you do. But my husband has a brother, and both boys have absolutely pulled away from their mum (thank god, she’s toxic). Because we can’t do anything with my side of my family without a comment, judgemental eye roll, sad sigh or negative opinion from her. We could see her ten days straight but one afternoon with my parents and we will get “oh and you’ve left me all alone”.
Planning anything, like Christmas, birthdays, outings, all a fucking nightmare because it ends up a continuous guilt spiral for my husband because of her sheer passive aggressiveness.
If I asked my MIL, bearing in mind it’s all intentional, she believes her own lies that she’s done nothing wrong.
Whereas, both boys in-laws are non-judgemental, positive, don’t interfere, enjoy their achievements, don’t make comments, offer help when it’s appropriate, and don’t make everything about them. Y’know, a normal family.
You may not SAY anything outwardly but I bet your responses, attitude and demeanour tell a different story. And it would be interesting to know what kind of relationship, independent of your son, you’ve tried to create with his partner. My MIL doesn’t even acknowledge me in my own home, I am purely the vessel to birth her grandchildren. She will happily eat my food, comment on my decor, tell me what I should be doing for work, but won’t thank me for my hospitality or even say hello when she arrives.