Want to do the jealousy thing and gloat about:
the wifely mood-swings & demands you can't deny because you're (officially, read the handbook) the one who did this to her;
the total loss of anything like normal sleep, sex, or mental functioning once the baby comes;
the way your parents and in-laws are going to laugh their butts off for the next couple of decades, especially once the little-love hits puberty;
and, the whole idea that you're breeding.
The problem is, I AM jealous, and even though I'm single my women are known for their mood-swings and rants about things I did to them, I'm not known for normal sleep, sex or mental functioning, my family members already regularly laugh at me regardless of their generation, and, well, somehow I don't think when they find out you're breeding there'll be guys in dark suits, shades & SUVs following YOU around mumbling things about "national security".....