How can I stop this? PLEASE HELP?

Almost every time I date someone they start to love me, and when they tell me that, it just sets off some kind of alarm in my head that tells me I need to break up with them. They don't even have to say love, if things get too passionate I'll just drop out of the relationship. Because of this I have the reputation of a player ( Which I do not want!) and it's happening again right now... Any advice?