You understand that football is a sport, a game, with few long-term consequences outside of the game; sex is usually a deeply emotional experience with many short and long-term effects on body and mind very different from sports.
Actual serious consequences is a big part of what drives people to view sex as very serious business. Most people are happy to see it as just another form of play time if you can nix the threat of death, maiming and babies with a fairly high degree of confidence.