cold saidTo me, a guy who doesn't have casual sex is a big plus. Because they know how to do without or don't crave sex, I think on average they're less likely to be unfaithful when in a relationship and less likely to be solely after your cookie jar.
... do you think this is true?
Could be for some guys. Let me give you another model, using myself as the example.
When I'm single I go into what I call "hunt mode." I'm a total slut. I go beyond casual sex to constant sex.
But as soon as I start dating a guy regularly that hunt mode switch turns off, all by itself. I get no credit for it, not a conscious decision, it just happens automatically. I was looking for a man, I found a man, I'm not looking any more. I have what I wanted and need, I no longer even look at other guys with lust. I simply lose interest & motivation to seek others.
I don't know how common a response that is, but I know I have it, and I would guess that at least some other guys do, too. The past is not always prelude. Some guys really do settle down and put their wild days behind them, as soon as they get what they were looking for all along.