Does a midlife crisis for a man always mean they're unhappy with their significant other? wondering if i should expect a break up

A mid-life crisis: takes many different forms. It could be realizing that you haven't accomplished goals, haven't travelled, haven't taken a break, etc. Mainly, it's the point in life where a person realizes that they have likely lived half (or more than half) of their lives & they start to take stock of things. A breakup is not a requirement. If you are concerned, then try talking with your sig. other about it.