I hate these people, too. Usually. But I find myself doing acting in this way toward my husband often. He will tell me about something from "back home" (the midwest), and I immediately have to top it with something oh-so-much cooler that's in New Jersey. Or I'll just rationalize that what he claims is so awesome is actually not that special at all.
I am careful not to do this with his accomplishments. I would never belittle my husbands efforts at work, school, in church, etc. In fact I remind Beardface regularly that I think he is the strongest, smartest, and most wonderful man on Earth. Why, then, do I feel the need to cut down everything he has seen or experienced before me?
I think on some level I feel rejected when he does that. As if everything we do together cannot hold a candle to all the awesome things he has done in his life before me. It makes me feel boring and like a bit of a homebody.
I know I'll feel better once I lay that feeling down and just listen to what my husband has to say. It's a place to get to; I know. But in the meantime, I'll be pumping up Jersey's image in my household.