Those thoughts are evil things rattling around your brain. They drive me batty when I'm alone! Just remember that though there might be an element of truth to some of them, you can't figure out which ones are valid. So just ignore them the best you can.
And the parent's meeting is painfully similar for me. Hard to see all these "happy" couples. Then I realize that 4 out of 10 will be divorced eventually... Makes me feel more "normal."
Detachment is hard. But it's not just a way of protecting yourself now; it's really a way of developing healthy emotional relationships that enrich your life instead of entangling it. Some men may detach easier than women, but others have just as much trouble. I don't think it's gender specific, but more relationship specific. I had no trouble detaching from my first wife when I chose to divorce her. I was done, wanted to find that spark in my life, yada yada yada. Karma turned out to be a bitch for me...