Repeatedly 'falling in love' with friends?

I am female. I find it hard to make friends. I might find one friend, become very emotionally attached to her, and then become obsessed and feel like I have a crush on her. Sometimes it's a physical attraction; sometimes only emotional. But it always takes over my life. And then the friendship has to end because she is almost always married and a colleague at work, and I am almost always so obsessively infatuated with her that it just eclipses everything I do. And I am alone and heartbroken again. It happens that way repeatedly; it has for many years, since I was a teen. I start out with no friends then end up with no friends plus a badly broken heart, to boot.

Where will this end, and is there anyone for whom this is normal??