Most Helpful Guy
There could be a number of factors. Perhaps they are trying to just get into your pants. If you let them, then the... Well... They "cum n go" . And thus you get hurt. Or perhaps the want to get into your pants, but won't put out... So they leave. Like I said, the reasons can be many.
Most Helpful Girl
Well the real question is what is the purpose of you dating in the first place? What are you views, morals, principals, beliefs and values about love, sex, marriage, relationships, kids, etc? Do you believe in premarital sex of any kind before marriage, or you believe that sex should only be shared with your spouse? What kind of men are you attracting? How are you attracting them and how are you attracted to them?
Do you speak to them about important matters such as that, or do they seem to deviate to things that is lust centered or other silly nonsense that is not important in dating? Are the guys your meeting based on preferences that are not necessary? Such as physical appearance which shouldn't matter until later on? What are your standards, and are they a must or their unrealistic? Matter of fact, what are you even looking for in a partner? And for what purpose? That shouldn't be happening if you're choosing the right kind of people to date. Or are you doing like what so many people are doing going for any and everybody who shows interest? And most importantly, do you REALLY need to be dating at all or is it a want just because? When you think about all of these things, then you will know what to do. It's best to have somebody else you trust ask you these questions and talk to you about them.