i'm not gay, but i am old and have had a lot of experiences. when we lived in england my wife and i had a wonderful gay friend. we loved him like a younger brother. we also had friends who were a much older gay couple who had been together for about 30 yrs.
i know that this experience is limited, but it does give me a small foundation from which to generalize. what george said in his post is confirmed in my experience. our younger friend was always "looking for mr goodbar" (if you emember the movie). he would find "mr right" only to find that his selection was distructive. he covered his depression by always being the life of the party. he was not alcoholic, although he did drink socially, and he did not abuse drugs.
i also want to point out that these exact same things can be said about many heteros and bi's. not being hetero does not make you any more wierd or self-distructive than most of the heteros and bi's that i've known in my life.
you did say one thing that concerns me. you said that you and your girl friend were having trouble communicating. this is a death sentence for any relationship - i don't care what it is. sex is great and wonderful and makes you feel good. but if you and your partner can't communicate, you only have a short-term sexual relationship. long-term relationships require commitment and commitment takes honesty and communication.
i hope this helps. i wish you and your girlfriend the very best no matter what the outcome.