Why do men want to have relationship but dont want to marry?

Marriage as it is defined today does not offer anything substantial to men. The world has become a massively competitive place in which to live, and perhaps nowhere else is this true as between the sexes. Everyone has something to prove, something to crow about, and something to set themselves up as superior to anyone else. I imagine that men don't want to have to return to their homes after a day of competing in their jobs only to face more posturing and strutting self-importance, more competition and headaches inside the walls of the one place he has to get away from it.

Statistically, a marriage has a better than 50% chance of failure, and usually for stupid reasons like "He doesn't thrill me anymore" or "I feel unfulfilled so I am dumping him". And yes ladies...women are the ones who file for the vast majority of divorces, and for idiotic reasons like these. Why should any man bet his entire life on a worse than break-even gamble?