A straight boy may have a few fumbles with a girl. Unlikely a gay boy would have done that.
Sometimes, in my haste, I write something stupid. Those two sentences prove it. Of course, a young gay man could have a fumble with a girl (some of them even marry girls), but not as a result of their own natural attraction.
What I wanted to say, was that there is a certain social expectation that a young man (understood as heterosexual) will have some sexual experimentation with a willing girl, but I wanted to juxtapose that with the situation of young homosexual man. There would be no societal toleration of his sexual experimentation with another boy.
That (in the past at any rate) likely made it difficult to gain some experience in who appealed to them and who did not.