if he hasnt choose you over another, then he doesnt actually love you, does he? When you are IN LOVE with someone, they become your first priority. If your not his 1st...the forget him. he just wants your company-thats it. Be creful though, cause he may be using u as a safty net.If he ever falls out the the other girl, hell just get with you, cause hell know uve been waiting 4 him.
You ride it out. There's not much you can be but continue to be yourself. If it was meant to be then that person will fall in love with you and you will be with them.
If not...Then use that love you have for them to build a closer bond to them and build trust, then you'll always have someone to turn to. You'll just have to learn how to control it. The heart in sould in aspects is endless. You will always be able to find love for someone else to help you past what you feel for others.
Everything happens for a reason. And it's never a bad reason. You falling in love with them could be so you pay closer attention to them to pick up aspects that you'll use later in your life,