It’s very sad when alienation happens for no good reason and the children are weaponised. Unfortunately it can carry on even when the children are adults. My SIL gets very angry that her son wants a relationship with his father. Her son still lives at home (he’s in his early 20’s & looking to leave) & when he visits his dad, she freezes him out, sulks, posts a lot of self pitying memes on Facebook (not that her son follows her on facebook!) & does things like taking her adult daughter out for lunch & not inviting her son! He still sees his dad regularly, is planning to move in with him imminently even though that will mean sleeping on the sofa, until he’s saved enough for deposit so all she’s done is lose her son!
Her marriage broke down because he had an affair. Whilst this was wrong, she can’t see that perhaps her refusal to increase her hours or get a full time job when the children were teenagers (she works in the NHS so plenty of vacancies) whilst expecting her husband to maintain a certain lifestyle for the family, which meant he was doing 2 jobs was a contributing factor. He met the woman he was had an affair with on the second job, she was also doing a second job. Interestingly, this behaviour is now being copied by her daughter.