I have to be honest, she doesn't sound like the most considerate person herself. For example, you and she started a sexual relationship, and then she got into one with your room mate, without any discussion about it beforehand. It's always a good idea to talk about sexual partners, since it affects everyone.
I didn't notice any mention of being "in a relationship" before the room mate sex incident, so I'm not 100% clear at what point you established that. If it was before she slept with your room mate, then I believe she could have handled that better.
You talk about "rules" with regard to their relationship. I'm curious whose rules these are? Not the nicest room mate you have there, if he's putting restrictions on her that affect you so much. And if they're her "rules" then why didn't she just come out and say it's what she prefers? Communication.
From the overall tone of your post, I get the sense that you struggle with self-esteem. By the sounds of it, she's not much of a catch, and you just dated her because you "didn't see any good reason not to date her."
The drug thing I can relate to. My girlfriend is totally anti-drugs. I just smoke a bit of pot now and then, and I did tell her that on our first date. She acknowledged it and then promptly pretended I'd never mentioned it (out of sight, out of mind). A month or two later, I had invited her to this folk music festival without thinking about the fact that there'd be pot all over. As soon as I realized it, I told her about that, and said that I would probably have some if it was offered. She wasn't impressed and practically broke up with me over it, until her husband reminded her that the chances of finding a polyamorous pansexual girl in our city who doesn't smoke at least a little pot is pretty much zero. He totally went to bat for me, and it saved our relationship. You see, I've got a lot of self-confidence. I'm not one to let other people tell me how I have to behave, especially if they're asking me to change. It's not that I'm so attached to pot that it's more important than relationships... it's the principle behind asking someone to change for them, when it's not something you want to change for yourself. In the end, my girlfriend liked the fact that I live my life for me and by my own rules, and not what other people dictate I must do.
My point in all that is that I don't think I would have made that promise in the first place. You were at a festival where stuff like that was all over the place, and clearly you weren't able to go find her every time something came up. She couldn't have understood that since she doesn't do drugs. Now, it's totally fine for her to have her principles: in the same way that she shouldn't make you change, nor should you make her. But if she's that hard & fast about it, and you're not down with that, then it's a sign of incompatibility.
Just from your description alone, I can see why men never dated her. She's inconsiderate of people's feelings, makes them change for her own purposes, and she spends hobby meetings sharing her sob stories. She forced you to make a promise that wasn't reasonable given the circumstances and then overreacted to your indiscretion. Finally she manipulated you into ending the relationship when you didn't want to, because she didn't have the bones to do it herself. It honestly doesn't surprise me that she would attract the kind of guy her ex was, it's that whole "unhealthy people seek unhealthy people" thing.
My advice for you is to spend some time on yourself. Possibly learn to develop your self-esteem and self-love. When you start dating again, date women that you "can see a reason" to date, and not just "no reason not to."
Gralson: my husband (works out of town).
Auto: my girlfriend (lives with her husband Zoffee).
The most dangerous phrase in the English language is "we've always done it this way."
Last edited by SchrodingersCat; 06-30-2012 at 12:22 PM.