Limerence?

I have a problem. A reocurring problem. I get depressed, and then I lead women on to me so that they give me attention, and then I become obsessed with them, and then I know that I have to detach myself from them, because I’m not looking for a relationship, I just want to ease the pain of my life somehow. And then I end up, not just causing more pain to myself, but hurting someone else too. This time it’s especially bad though. Because this girl is 14 years old. I thought she was older, maybe 17, and I should have stopped leading her on immediately when I found out how old she was. But that was more than three weeks ago. And just now I realised how bad it is. I know that she likes me, and honestly I like her too. But that’s exactly why I have to stop. I don’t know how to take responsibility for this, really. I could have done the right thing, and then neither of us would get hurt, but now it’s too late, and both of us will. And it’s my fault.
Why do I behave like this? When I know what is right, why do I convince myself that it’s actually not that bad? And it’s not like it’s the first time I lead someone on, knowing full well that a relationship is not possible. I don’t know how to be happy. And when I’m unhappy, I try to be happy. And I do things like this. And I fantasize … but it’s not real. It can’t be, even if I want it to be, because she’s too young. And I’m 20 years old. I’m an adult. I should know better. And I don’t want to pity myself either. I’m not sure what I want. Even if I knew, I don’t think it would be good for me. I’m just trying not to self sabotage, and to keep myself stable somehow.