If you like a friend of yours as more than a friend, and don’t tell them, and then they start dating someone else, you have no one to blame but yourself.
What have you got to lose? Chances are you’re not going to stay friends with someone you had a crush on if they get into a serious relationship with someone else, so why not tell them how you feel?
If you are in a relationship and don’t speak your mind about how you want to be treated, or touched, or teased, then don’t be upset when your partner disrespects you, or isn’t affectionate, or doesn’t know your limits… because you never made your expectations clear!
People are not mind readers, you need to tell them how you feel and what you’re thinking. If you are honest with your words (and your actions support them) and the feelings are not reciprocated, then at least you put it all out there and will have no regrets.