Seriously though -- my feelings about casual sex change back and forth. (Probably depending on how long I've been out of a serious relationship.) Though it can leave me feeling far from fulfilled, as long as both people approach it as physically intimate recreation I don't really have a problem with casual sex. I do have a problem if it involves cheating on someone else -- that I don't do.
I agree with Kumawool: an 8 year difference in your ages isn't really that much. If he's mature for a 21 year old and you are both attracted to each other, I say let your friendship develop and see where it goes.
Being ready for a new relationship after leaving one is another matter. Only you know when you're ready, and it is good to give yourself some time to recover. I don't believe there's a magic amount of time to wait. That totally depends on you, your sense of self, the nature of your break up, and other factors. Communicate with your friend. If he is really interested in you, hopefully he will understand and be patient.
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