Am I using sex as a means to an end?

I have a couple relationship experiences and all of them started as hookups. Then once I'm securely attached to them I loose interest in sex. I still find them sexually attractive and get turned on by them but I never get motivated to follow through to the end with sex. It hit me that I might not be the most sexual person, but I use sex to initially attract a partner or as a cure for loneliness. As soon as I have a partner and the loneliness is gone, I loose interest in sex. Does anyone else have this experience?

Also, another factor is that so far all my partners had consider themselves as exclusive tops, while I realistically consider myself vers btm base on my sexual history. I probably would be more vers if I didn't attract tops. While I do enjoy bottoming, the amount of work it takes me to be ready makes it hard for me to want to do it.