Most Helpful Guy
Because he loves her and the present state of the situation?
Marriage isn't necessarily the best way to cement a passionate and fun relationship. Society tends to view it like the ultimate act of love, when it should really be like the ultimate act of something else -- some practical need like children, a desire to share the same income and get a tax reduction, etc.
It usually means a change in the type of friends you have, and potentially a lot more time spent with other married couples, family, etc.
Marriage changes everything. At least from the male perspective, it's the end of a lot of freedom, like the freedom to just have your own spending money and do whatever with it (go bar hopping with friends, e. g.). It's the end of a carefree lifestyle.
And that can strain everything -- and possibly even distance the husband and wife apart, make them no longer feel so passionately about each other even if they still love each other.
A man who loves spending time with a woman on his own terms, and of having the energy to act spontaneously on a date, while simultaneously spending a lot of time with bachelor friends and so forth could easily ruin that whole dynamic with marriage. It's not the wisest choice for two love birds who are really having a lot of fun.
It's a good choice for two people who want to settle down, decide they've had enough youthful fun for their lifetime, and can just start focusing on their career, family, etc.2