Boyfriend's mom's odd behavior

I am posting this for my 29 year old boyfriend. He and I have been together for 4 years and have lived together for the majority of those years. He is looking for a healthy way of dealing with his mother's odd behavior. We live in a city three hours from the small town where he grew up. He is the oldest child with a younger broather and sister. He goes home to visit between once or twice a month. I go with him occationally but he goes by himself the majority of the time. To some degree the frequency of his visits use to annoy me but now it does not because I better understand the guilt he will have to endure if he does not Even with him going to visit often she still gives him a lot of guilt about not spending enough time with her. She is coniving and plays games instead of talking about her feelings or why. His parents got divoursed when he was in school around age 20. His mother is remarried and has a 4 year old son she adopted with her new husband. She just had another blow up over my boyfriend not spending enough time with her. He was there for the weekend and spent both Friday and Sat night with her from 5:30 ish to 10:30 ish but she started in on him about how he does not spend enough time with her. My boyfriend is a pleaser and a moma's boy but also a man. He has actually done a lot over the last year to be a man and stand on his own feet and deserves a lot of credit for it. Can anyone give him some advice on the best way to handel this situation? Or maybe explain her motivation to me? I just think it is very strange. His mother is important to him and I want to help him deal with this the right way so that he can have a healthly realtionship with her. Right now when she throws a fit he tells her what he thinks but then trys to "please" her and spend more time with her to the point he does not enjoy his visits. The entire time he is just trying to make sure everyone gets enough time.