I think a little bit of jealousy is good in a relationship, nothing that is actually tangible, but something that sparks that constant rememberance to keep your relationship fresh instead of letting it get stale. It's a shame that when relationships get to that comfort stage people forget to add the splashes of romance and creativity that keep the spark alive.

Of course, pull out your hair, grind your teeth, and bleed from the anus jealousy is bad. Real bad.