But the biggest part is knowing that you made one in the first place, and being willing to learn from it. I think that, just a little, emotionally you are tired. But anyway this is all stuff that is a part of life growth so observe it and walk away.
Relationships are never easy.
The thing is that once you sleep with someone, it is harder to break it off - especially if you are not a person who runs around a lot. You have to be prepared for failure once you open your self up to love - not even love, but if you let someone in your world the possibility is there to get hurt. Be prepared for the fact that this might not work out, and be prepared to deal with it. There is always going to be disappointments in life. The thing that makes us or breaks us is how we deal with them, but never let disappointments stop you in your tracks.