First, the man who doesn't call you is not interested and you should be glad you found out sooner rather than later. Yes, it hurts. You feel cheap and used. Well, don't. Turn it around. See the situation as you using him. He wasn't that great anyway and there are plenty more where he came from.
If you must know, the reasons he doesn't follow up can include any of the following (and trying to determine which one it is will drive you bonkers, so don't):
- He was in it for the conquest. His mission is complete.
- He has a woman he's emotionally attached to and he doesn't get to have sex with her, so you took care of the physical part.
- He's embarrassed about his performance.
- He feels too much pressure to meet some standard you've set for allowing a man to sleep with you.
- The sex wasn't enjoyable.
- He's not ready for a relationship.
- He was drunk and horny.
- He has been rejected by numerous women over the years and now he's getting even.
None of those reasons are painless, but you get to decide the intensity of the pain and how long it will last.
Society frowns upon selfishness, but I suggest you become more selfish. If you're considering sleeping with him, consider your motivation. If you're sexually hungry, say it and do it. If you're desperately seeking a soul mate, you're putting a shit-ton of pressure on the poor fellow unless he happens to be honestly looking for the same thing and the stars have aligned.
It's that goddamn oxytocin messing with you. Fight back, Babydoll. If you concentrate on what you want now instead of many years hence, you'll enjoy the ride. When you decide to get naked and sweaty, if both minds are blown, you'll probably get the call and your relationship will blossom. If you're on the sexual see-saw at the top looking down at him, you'll need to avoid staring at your phone tomorrow and steer clear of the chardonnay and sappy movies.