Oh no! You have been moderately nice to someone, and they do not want to sleep with you! *surprised gasp!!*
Really now. Falling in love with your friend sucks, especially if for whatever reason you decide to not tell them. I've been there. Doesn't need its own term, and especially not being constantly reminded of oh how-so-terrible it is.
Fun fact: If someone's not into you, then that's pretty much the end of the matter. Instead of being an entitled little whiner about it, try moving on and finding someone else who is. It'll almost certainly lead to a much happier life for you.
The "friendzone" doesn't exist. If you want more than friendship, then speak UP. If your love is requited, then great! If not, move on, find someone else. Women aren't machines that you put kindness coins into until sex falls out.