Think how tough it is to be a buck. The girls only give it up for a few weeks every year so during those few weeks you have to be on the move all the time getting what you can when you can.
And during those same few weeks you have guys with guns all over the place trying to kill you while you are running around with booty on your mind. Yet they do succeed in getting enough of the girls pregnant to ensure a good crop of fawns for the next year.

No wonder they look so stressed out by the end of the rut.