Matt (or any of the boys) has the sudden realization that he is in love with not one, but two of his friends (the other two) after or during a D&D session. He then goes to tell the two, because it's been driving him crazy for months and he can't take it anymore. But to his surprise they both feel the exact same way. Cue very hot make-out session.

Bonus cookies for love confessions, cuddling, and fluff.

Even more bonus cookies if all (or one) of the boys freak out about the rest of their friends finding about their relationship, but no one notices anything different (just maybe that they are calmer.)
Or all of the friends have already figured it out, totally support them, and even had a betting ring on how long it would take for them to realize the truth.