So, what are you asking? If the Church is wrong, then… what?
First you propose that the Church might be wrong, then you propose that the reality of the misery and dangers of the active homosexual lifestyle be ignored, then you propose that a person cannot possibly be happy unless they have everything they want.
Well, what if people could nto be happy unless they had everything they wanted? Either you’d have a lot of miserable people, or you would have a lot of lawless people who would then make others miserable.
What if the teachings on homosexuality were wrong? Well, a lot of homosexuals who followed Church teaching would have been spared a lot of misery *despite *the error, if they followed Church teaching, no?
What if the Church were wrong? Well, what if? So what? Following *all *Church teachings leads one to be a better person, and when a society follows *all *of Church teaching, there is a better society.
So in answer to your question, what if the Church is wrong about its teaching on homosexuality? Then there were be even more miserable people around.
One of the beauties of the Church is that if you study the teachings as a whole, you see a beautiful way of life which creates a wonderful society and you see an interlocking set of teachings which is so far beyond anything which man could come up with that in itself proves the truth of the teachings.