Most Helpful Guy
"Because I don't want to make the first move to ask him about us." - YOU MUST and HAVE TO!! Especially if it's not what you want.
Only he can answer this for sure, but I'm guessing he is developing feelings. But you have to find out. Communication is extremely important in any relationship, but especially in a fwb's one! If someone develops feelings, you have to get it out in the open and talk about it. Does the relationship continue or do you need to end it? Do you become more, or not? If you leave it, it will end badly if it's not what you both want.
Most Helpful Girl
Have you talked about what you are both looking for?