Hi there. Okay, so I've been dating my best friend for about a month now, and she's really in love with me. I want to be in love with her, but ever since we started dating, those crush-like feelings have gone away. I now feel nothing but guilt towards her and I kinda want to break it off. But I don't want to break her heart: she's my best friend, and we've been through some crazy shit together. This isn't the first time that I've started dating someone and then instantly lost interest in the relationship. Am I doing something wrong? Should we break up? Do I tell her? What should I do?
tell her the truth and let her decide
You really do owe your "best friend" an explanation. You should not feel guilty for telling the truth. You will probably lose her as your best friend, too. So be prepared for that.
Now about your repeated HABIT of losing interest after the chase is over: In my day, a guy like you would be called a "player" and smart girls avoid a heartbreaker like you. You either get bored easily, are not ready to settle down or are unable to really commit to another person. Until you find out, cool it for a while. You are now getting a reputation of being a "player.'