Best Friend's Filthy DILF

Why do I feel this sudden, uncontrollable attraction to Mark, the hot football coach from college? It doesn't even make sense - I'm 100%, fully straight. Nothing can ever change that and yet the older, imposing man stirs something different in me. Every time that we practice football and his body is all sweaty, it's like a torment I can never escape from. And it all gets so much worse when he invites me to a party right in his house. I have to 'enjoy myself' right in his guest bedroom to feel less desperate about it all when I, then, notice something strange coming from the swimming pool. The cocky, married instructor is swimming and he wants to give me a few lessons... Characters are 18+