Man. It sounds to me like this is a terribly unhealthy relationship that you have. I realize how easy it is to be infatuated ("in love") after three months, but with all this conflict between you two, it sure seems like maybe it's not meant to be.

You both sound like you have some growing up to do. My boyfriend and I were "in love" after three months (well moar liek after 3 days hehe), but we were both well-adjusted people who had been in enough previous relationships to know how to behave. There is a difference between instant connection and instant attraction - sometimes you get both, and sometimes you get one and think the other one exists just because of it. Maybe you really like this girl and to her it is normal to say "I love you" so early. You have insecurity issues (as you admit yourself), so hearing that from a woman's mouth is going to blind you more readily to any flaws you might have otherwise seen as dealbreakers (like a tendency to spend the night out with other men all the time).

I think it's absolutely silly that she's spending the night at other boys' houses. If I wanted to spend the night at another guy's house, it would never be someone that my boyfriend didn't know or wasn't comfortable with because I love and respect him. Furthermore, if I ended up crashing at some guy's house, it wouldn't bother him because he loves and respects me. I am not forbidden to do anything, but I also do not abuse that freedom and trust.

In other words, the dynamic has to kind of just exist. It can't be forced by one of you and not really be accepted by the other. You don't want to let go of this relationship because it validates you, and that is totally understandable. But it's also not a good enough reason to stick around.