I've been with my boyfriend for 4 months and he is already losing interest. About a year before we started dating, he ended an on again, off again, tumultuous relationship with the mother of his child. She is very manipulative and controlling with everyone in her life and is the main source of our fights. (e.g. She asks him if we're fighting, she finds excuses to call him when she knows we're together, she complains that he goes places with me that he was supposed to take her when they were together, she greets him and ignores me when she sees us out, etc.) I don't think he would ever want her back, but he won't just stand up to her and keep her entirely out of the personal aspects of our lives.
Other than the ex, he sometimes is not very interested in sex (he's more than content to have sex once a day, I would like more). He says it's not the same with us (sparks, etc) now as it was in the beginning and that he is bored and unhappy with me. I feel like I'm doing my part to be a great girlfriend and that he's trying to find reasons to break up. He is used to being used and mistreated with the person he dates and I don't think he can understand or appreciate what a normal, healthy relationship is all about. We are in our early 30's. I don't know if this relationship can be saved. He does talk about getting married in the future (he didn't discuss marriage with his ex).