When does a man leave a woman?

Question

do most men stay with their current girlfriend until they find another?

Answer 1

Most unhappy men will do this.
There are a fair number of stupid ones that do the sneaking around thing just to have the thrill of not getting caught.
Normal guys in an unhappy relationship will cut the ties to the bad relationship first.

Answer 2

They usually already have someone else in mind. Men hate to be alone so they very seldom end a relationship with no one else in mind to be with.