I had one crazy ex and it didn't last for a long time, but she sure was crazy. Met her at a party: she was the friend of a friend and we ended up talking almost the whole night. She was really beautiful, nice personality, funny, liked music, had a part time modeling job, etc. We hit it off big and ended up having sex in the bushes next to the appartment complex the party was at.
The next morning, she had written me a long letter telling me how much she had enjoyed the night and how she felt we were soul mates and all that jazz. In retrospective, alarm flags should've gone up, but they didn't. I was coming off a long (sexless) relationship and she really was a stunner. The fact that I was also batting way out of my league blinded me to the fact that she was, shall we say, taking it a bit fast.
We ended up dating for a few weeks and she kept talking about having our own place. She was again taking it fast, but my lease was coming to an end and I had been paying the rent alone for a while, so I agreed to let her move in. That's when the wheels came off.
Almost from the first day she moved in, she started to talk about havind kids. When I told her it was crazy, as we had only been dating for 3 months at that time (plus she had just turned 19 and I was 22, both still in school), she started to flush her pill in the toilet in the morning (I saw her do it once, but it was 2 weeks after the "I want kid" conversation). She also was jealous of every living thing interacting with me (coworkers, family, pets, etc.). And she ate nothing but toast.
I caught her kissing some guy from her job and I learned from a mutual friend that she might have been boinging another on the side. I kicked her out after about 4 weeks of cohabitation. There wasn't much of an aftermath strangely.
I heard from a year a year afterward and she was married to some poor schluck and was pregnant with her first kid. Fast forward to last year, she tried to friend me on Facebook (for reasons unknown since I dated her around 2005). She's on to her second mariage, 3 kids and weights about 400 pounds. now.