There is nothing wrong with waiting for sex in a relationship.
There is also nothing wrong with having sex right away in a relationship.
You can sleep with them on the first date - good for you, that is your choice. You can sleep with them on your wedding night - good for you it's your choice. You choose to never sleep together but continue a happy relationship? Good for you, it's your choice and your partner for understanding
You shouldn't shame people for the choice they make, there is no right or wrong way to do it in the world. Perhaps everyone each has their own version of right/wrong that they follow, but I promise you that not everyone has the same rules. That's fine, that's great, we all have our choices don't shame others for theirs.
Before Amy I always had a theory Sheldon was asexual, but since he is considering it with her - my headcanon is he is demisexual
He has a lot of reasons to never find sex appealing, and he is considering changing them because he loves her and from what I can tell is begining to want her - so it's slow for him, he will get there and if he doesn't - if he flat out states that he will never have sex because he just can't, I think Amy will stay with him - but that's just me, I've always seen emotion over physical aspects in relationships. As long as they love and support each other, they'll be ok, they don't need sex as a make/ or break deal... Some couples might - but I don't think they would