I'm fairly certain that we are talking exclusively about relationships between consenting adults. At least, I am.
All I am saying is that we need to be careful not to conflate one idea with another.
I thing it makes a much stronger argument to do what you just did which is to focus on the right of adults to consent. Using an argument where you replace A with B, and then show how the argument fails with B, is not always a valid way to make an argument, IMHO.
You;re right that discrimination is not wrong - but discrimination without an actual basis beyond "sexual orientation" or "skin color" and so on is.
Right, so we need to ask why some people think it is ok to discriminate on the basis of sexual orientation but not ok to discriminate on the basis of race.
Don;t fall for the bigots' arguments.
Don't commit logical fallacies.