Aren't we designed to be together about 4 years? What evolutionary purpose does it serve?! Such as the story about Marnia and the guy she met who who psycic predicted was her soulmate- that lasted only a month?! I thought if it was real it would last longer than that. Occasionally you hear of a relationship that was great at first and then ruined by sex- mostly for teenagers but not all. I don't understand this. No offense. Comments?