It didn’t have anything to do with it at all. While yes, Matt had slept with a volleyball player and there was some fallout from that (these are adult college students, not minor high school students), it wasn’t what got Nick killed. So my theory was that Nick found out it was actually Matt who had assaulted the players and Nick was framed for infidelity and killed in order to protect that secret.
An undercurrent running through the show had been Nick’s shady friend Matt, who seemed at first like he was covering for Nick sleeping with the volleyball players under his care. At this point, I thought I had it all figured out.