Care to tell us about the first guy you seriously loved? Mine was called Dave, and I was in my late 20s. We lived in a flat in Dublin with his cousin and the cousin's girlfriend. When I first met him, Dave told me he was bi, and when we lived together, he had regular sex with a woman Katja (the letting agent for our flat). I didn't see her as a threat - he was coming home to me every night. But one day he met another guy in a bookshop and they started a relationship. I was devastated but the final straw was when one evening I came home from work, and was told they were having sex in my bed.
I moved out shortly afterwards, but was obsessed with him. About a year later, I visited him in his new place (I've no idea how I found out where he lived - pre internet days). We were having a pleasant coffee when his new partner came home from work. He was gorgeous! My obsession faded quickly after that, although I still think of him today.
I feel better having told this story. Be nice in your replies - I'm feeling emotionally fragile right now.