My SOs mother seems controlling

-Thank you all for the input. I'll be addressing this to him today. I have come to the conclusion that he is at fault just as much as his mother. Although this is the first year that he has ever done this, I will give him the end of the month to come back before I decide to move out of our apartment-

So in May, my partner decided to visit his parents for 3 weeks since he now works remotely. 3 weeks turned into a month and well.. he is still there. I sometimes ask when he plans on coming home and I always get similar answers. “My mom wants me to do this and that.. My mom told me to stay longer.. My mom says xyz will happen if I come back..” I have never met her before but he usually refers his family as “toxic” which is why I have yet to meet his parents (mostly because his father was abusive during his childhood). I have no problem with him visiting them however it is the way he talks about his mom which bugs me. It is almost as if he needs his mother’s permission to come home since she continues to pursuade him to stay there. He is a grown adult. He booked a flight back a few weeks ago and she told him to cancel it. It is understandable that she wants to spend time with her son, but it is almost as if she is keeping him hostage at this point. He calls me every day/night and tells me how much he dislikes staying with his family.

My main frustration is that I did not expect to be in a long distance relationship and if I had known, I would have asked to talk about it more in depth. This is not the first time this has happened. He went home for Christmas for a week and came back a month later because his mother asked him to stay. Even when she visited him before we were really serious, she kept pestering him to move back in.

Has anyone experienced this before with their partner? I honestly do not know what to do other than just wait for him to come home. Like am I overreacting or is this weird?