Mothers

This morning I spent a few hours (torturing myself) thinking about mothers of ex-boyfriends. I'm not sure where this came from but I realized that I have dated several guys with mothers who either a) were beyotches b) disliked me or c) went really out of their way to make me uncomfortable or d) all of the above. I'm fine with the fact that they may have been unfriendly (cruel) people, or even with the idea that they didn't like me, although I can't really pinpoint what would have caused that feeling.
What is frustrating about these mothers is:
1. I stressed out so much about whether they liked me. Funny when I think about it now because who cares if the mother of your 18-year-old boyfriend approves of you? Chances are you won't be getting married or even move in together, and if she doesn't like you that means you won't have to suffer through awkward family events that always prove embarrassing for both you and your BF. I wish I could go back to those days and take back all the effort spent trying to impress these impossible mothers.
2. I was a great girlfriend, especially to these particular guys. I was a good student, had one or two part-time jobs, was polite and friendly and very much into the guys. I helped them with their classes, encouraged them to get their lives together and in a few cases I was the reason they stopped drinking/smoking/generally wasting their lives. It's so ridiculous now that I think of it - some of these guys couldn't hold down a job or pass a university course, and I was the one getting attitude from their moms?
I wonder how they treat their sons' current love interests (or maybe wives...not sure if any of these guys are married...). My bet would be no better - some people are just impossible. I'm just happy it's no longer my concern.