Many guys (and girls) get lazy once they are settled in to a relationship. Oftentimes, the guy has less power, because girls that are younger and hotter can easily find other guys who will befriend them. Additionally, girls are generally more social than men and value their friendships more. Men more easily disregard previous friendships once they settle into a relationship.
There are exceptions to these generalizations, but the point is tha being a boyfriend does not stop you from becoming a man in all areas of your life.
It still means dressing well, waking up before noon, and going to the gym. It still involves living a full and fulfilling life. It also means that an attractive boyfriend will stay in shape and stay attractive to the opposite sex, not to bed them, but rather to remain competitive in the marketplace should he one day lose the girl or choose to leave.
Having Boyfriend Game means being a man of high value, for life. Therefore, regardless of his marriage or relationship situations, he is always happy with himself and knows that he lived to the best of his ability.
Most guys have no idea about boyfriend game and most guys feel lucky having a girlfriend, when in fact in should be mutually satisfying.