As Jack said, Ennis could "make it on a couple of high altitude f***s once or twice a year",(and presumably the countless times he masturbated thinking about Jack, as mentioned in the ss), he just didn't need sex in the way that Jack did, or maybe he just didn't see the point in having sex with anyone else knowing it would never be half as good as it was with Jack.Whatever the reasons, even if he did desperately need or want sex with another man, he wouldn't have done anything about it, even if he had the opportunity, he wouldn't even admit to Jack or to himself that he was gay, he would hardly admit it to a complete stranger.
I sometimes wonder if he might have visited a female prostitute after that first summer together, because of the line in the Motel scene in the ss where he says he likes doing it with "women", when the only woman we know he's been with is Alma. Maybe he wanted to prove to himself that he wasn't gay, and the relationship with Jack was indeed a "one shot thing", before he married Alma
