The slim chance of people falling mutually.

/Hello everybody,
This is been on my mind for quite a while, I just wanted to get it off my chest and maybe get a discussion going to have more insight.
We know everybody falls in love once and a while but what is the chance that that love is mutual ? Or does it just then progress as the other person admits she/he is fallen in love ? Seems like a very slim chance to me.
For example I really get along with this girl and we really like each other and I have fallen in love but I'm pretty it isn't mutual.
although I get along with alot of females and I've never ever had the fortune of being loved mutually.
Can people with more experience give me some insight ? Or doesn't matter just participate in the discussion I'm really interested in what someof you have to say.
Kind regards.
Btw I'm 19/20