I'd be damn if I'm going to sit in the cave taking care of junior and not get some strange myself if hubby is out getting it.
Once all is said and done, it really isn't difficult to be monogamous. The laws of attraction are always in play, it is just a matter of will power. Some people are just weaker then others in that department.
Generally, people are only as strong as their options. The fewer the options, the more monogamous they are. Sad, but true.