Thanks for writing to Just Answer.
Men have a very different attitude about sex than women do. (of course, these are all generalities)
Men tend to see it as a purely physical exercise. They can have sex with someone they have absolutely no feelings for. It feels good, and for some men, it boosts their ego to sleep with a lot of women.
They also like the competitive aspect of "winning" the girl..and this can make the girl more valuable to him. (which is why the girl who is always available never gets the guy)
Sort-of taken means that he has a girl who thinks he's with her, but he's sleeping with anyone else he can find. It is also his way of telling you that all he's offering you is sex, with no chance of a commitment or relationship.
So yes, he is using girls at whatever level they allow themselves to be used at.
I can't tell from your note whether you have slept with him or not, but the fact that he is saying he wants to see you "later" in an evening suggests that perhaps you are.
If a man sees you as someone who is available for sex on call, he will use that opportunity when it's convenient for him. But if he's out, and sees something better, he will go for it, as he knows that you will be available any time.
The danger for women in these situations, is that typically if a woman has sex with a man more than 5-6 times, she begins to build an emotional attachment, (even if in her head, she thinks she's find with the arrangement). It seems to be hard-wired into our make-up.
If you want to learn about how men think, XXXXX XXXXX has written a wonderful series of books that give the male perspective. Having an understanding of how men think can help you stay out of situations like this one in the future.
This is not a situation that is going to build your self-esteem, or help you find a man who loves and respects you. If you're not involved with this self-proclaimed 'slut ' of a man, great! If you are, I hope you will consider seeing a counselor who will help you rebuild your self-esteem, figure out what your boundaries are, and support you in finding a healthy relationship where you are valued, not used.
I wish you all the best in finding a man who loves you,