From a completely different direction: the phases of underwear

I have long held a theory that marriage can be broken down into phases that are associated with underwear. (this applies mostly to guys)

Phase 1: You are clothed most of the time and your spouse doesn't see your underwear (except the "good" ones you wear on dates)
Phase 2: You comfortably wash your clothes together and see each others underwear. Each still buys his/her own.
Phase 3: You ask your wife to pick up some underwear for you when she is out shopping.
Phase 4: She gets you underwear as a gift (birthday, Christmas)
Phase 5 (this is the most important one): Underwear becomes a substance that you no longer think about it. You do not buy it or throw it out, but somehow, you always have clean underwear in good repair in your drawer.