According to my information, women are attracted to men in a stable relationship because these men have already been "tested".
I doubt it has to do anything with pheromones, or with behavior. The knowledge that the man in question already has a stable commitment itself is what makes him more attractive to other women.
Some other problems with a vacuum:
1) Water boils immediately. If your skin is damp, you'll lose a hell of a lot of heat that way.
2) You will still lose heat to radiation, but whether or not you're in sunlight will determine how quickly you die. Sunlight in space hits Earth at around 1000W/m².
3) The air in your lungs will REALLY want to escape - you might have a hell of a time holding in 14.7psi.
Well, nope, your blood wont boil as such because your body is solid enough to keep the pressure up high enough.
If your blood really would boil as a whole, you would indeed explode, as one liter of water IIRC translates to 1,700 liters of steam.
And yes, you cannot just hold your breath in the vaccum.