My boy friend loves another girl..but he still has sex with me. I'm just time passing love for him. Now, how to handle this situation?

I am curious... Is he in a relationship with this other girl that he 'loves' .. And is cheating on her with you?  Well .. If that is the case .. Then understand that you are 'the other woman' and are not blameless in the hurt and devastation being inflicted on his partner.

If he is not in another relationship, then .. Either accept the fact that you are engaging in casual sex, and not a monogamous relationship  or don't... THAT is your choice.