There are probably several reasons why this happens.

If He Asks for Sex Early, then He Doesn't Care about Your Welfare

It doesn't mean that the guy doesn't care, In my case I expected the girl to stop me if the time wasn't right.

First and foremost, if he is asking for or expecting sex early in a relationship, it is clear that he is simply interested in fulfilling his own pleasure and not in your welfare or feelings.

I agree...let me tell you about my experience.

He has invested very little in the relationship and has not made a commitment. If that's the case, then of course he would have no problem dumping you when he no longer has a use for you or is ready to move onto the next exploit. (By the way, women are also guilty of this!)

Men Don't Respect Easy Women

Unfortunately this is true of some guys. But no guy has the right to judge you.

Secondly, most guys really don't respect women who are "easy," even though they (the guys) initiate sex.

You're half right. If that is the way that the girl feels about sex, she should make sure that she is with a guy that has the same understanding.

Only a man who will respect a woman enough to deny his physical desires and take things slowly is really worth having. He realizes, as the old adage says, "Good things come to those who wait." To abstain from sex means sacrificing his desires in order to honor and respect you and to treat your body with dignity. An honorable man like this is looking for the same kind of woman in return; one who respects him, and HERSELF.

To best illustrate what I am trying to say, let me quote from Elisabeth Elliott's book "Passion and Purity." Speaking of abstinence, she says:

It can be a relief when she says no... because he finds mystery in her, and mystery is both surprise and delight. Keep your distance, I say to women. Recognize that fundamental anomaly of human nature, that we prize what we cannot easily get. We take for granted, we even come to despise that which costs us no effort. The bicycle given for Christmas will not be prized like the bicycle bought with the money earned by delivering newspapers for two or three years.

...If there is one reason why sex becomes dull and a bore, it is that it is commonplace. It's available anywhere, everywhere, to everybody who is looking for it. Nothing is kept in reserve. No pleasures are saved for the wedding night, let alone for the bride and bridegroom exclusively. I'm not really quite a sentimental woman. Some of my reserve has nothing to do with militant morality, or even Christian principle, but with the very real pleasure of saving things up. (Page 145-6)

You are Playing with Fire

I believe this is one of the reasons why God tells us not to have sex before marriage -- there is always a possibility of getting dumped and hurt. And it doesn't matter if you agree with God or not, it's still true. You are playing with fire, and you will get burned. Whether by disease, by a painful loss of self respect, a bad reputation, or the intense pain of a ruined relationship -- whatever the form, it will come back to bite you.

If a Guy Can't Commit, He Shouldn't be Intimate

If a guy doesn't have the decency to commit to you, he shouldn't have the privilege of being intimate with you - a privilege that was created by God to be enjoyed within the confines of marriage. God loves us and only wants what's best for us, so He created sex and physical intimacy as the ultimate (and safe) experience within the context of a committed marriage.

So, instead of wasting any more time and heartache being a victim of this game, stand up for yourself and do what's right. Respect yourself and your body! Set firm standards for what you will tolerate and how you will be treated. And most importantly, wait until you get married to give yourself to your husband.