I've been seeing and having sex with this girl on and off for a few months now and every now and than things will turn out bad. The first time we hooked up like twice and she said that we should just be friends. I was not having it and told her no. A month after that we got back together and hooked up again. We kept hooking up on and off with the same situation.  She'll want to randomly have a talk and she'll tell me that she isn't ready for a relationship and she wants to just be friends and I'll be super cool about it and tell her to be happy well end up fucking that day and the cycle repeats. This time she said the same thing and also added we cant have sex anymore becuse she is getting her birth control taken out, I remained cool but I think we ended things for good. Two days after she saw a picture of another girl on my snapchat and messaged me saying "this is why we could never date it's only been 2 days". I told her that it wasn't anything and that it's nice to know she has feelings for me. She said I didn't think you'ld move on in 2 days anyways but its cool. We haven't talked since. I'm just confused. Idk what went wrong. She says I'm perfect and there's nothing she doesn't like about me but she can't commit. Idk I'm just bother by it all.

Reminds me of a lot of women in cliche filled soap TV shows.

People with insecure attachment styles associate the dramatic high 'highs' and low 'lows' (that roller coaster feeling) as a sign of falling in love. So if they ever date someone who has a secure style of attachment they'll often complain of the relationship being "boring".

Hypothetically speaking, if the girl was with a boyfriend for two years, and that relationship was indeed emotional roller coaster, do you think this girl is "damaged" for every next guy she meets?

Her every future relationship won't be something that triggers her emotions like her ex did. See the problem?

I'm not sure what your point is, however, so if you can elucidate on it perhaps I can answer your question more directly.