Koi ga Bokura wo Yurusu Hani

A story about two men that have been best friends for years, knowing the fact that they have feelings for each other, and ignoring it. They discovered it on their college days and settled the matter with a time limit; if they hold the same desire years later they will do something about it. Now both of them have girlfriends, but it seems that their desires only grew stronger, in spite of loving their women. So, what happens when their girlfriends agree to make them indulge in their desires?, and have a relationship only between the limits that desire allows them...

This is a bet, to know what is stronger, love or desire?