why young lady.

When a person cares about you, you have the power to hurt that person. If you do hurt them you have a momentary rush to your ego making you feel "empowered". You cared more about feeling empowered than you did about them. Try being a little more caring and compassionate in the future. Don't be an emotional parasite.

Good for you for not falling for his looks when you know he's not for you. But, you may feel even more empowered if you are able to act on the physical attraction WITHOUT developing feelings for him. Isn't this what men do all the time?

You had a visceral response. That may have been inner wisdom. Women are deeply intelligent.

I'm going to go out on a limb and say that your feeling of regret is just the 'doubting' side of your mind trying to get the best of you. Go back to that empowering feeling you had initially. Don't just think about it, feel it. That is likely more the truth of the matter but maybe you just lack a bit of confidence. Physical connection is great but not enough if someone is "clearly not for you". This may have represented a new level of choice for yourself (compared to past choices) and it's natural for that to feel a bit odd, but no need to doubt your resolve and why you chose 'not him'.

that be the way :)

Doesn't sound like you became physically involved with this guy. Is it just someone you physically lusted after?

this is the story of my life. you regret it for a lot of reasons. For one, physical connections are intense. Often drug-like. When you turn one down, it's hard to shake. Second, you didn't see it through. When we don't see things through, we are programmed to then always wonder what would have/could have been. Third, we often do want what is bad for us. It's the classic story.

The op is not "young"?

You freindzoned him