I have this crush…

It sounds like he's moving on. It may be because you've been in a relationship before, he may think because it didn't work out then it won't work out now. Maybe you should tell him how you feel if you're serious about him and see how he feels in return. Sometimes relationships just aren't meant to be so don't get your hopes up too much. Good luck.

From what I know, guys can be just as stubborn as females can be. If he persists on trying with the other girl, then he must hold a great deal of admiration for her. He must really like her. Be there to pick up his broken pieces if he breaks his heart in the process. I've been in a situation much similar with yours. Sometimes it's not really meant to happen.

Be there for him and sort of watch over him, if you care for him you wont want anything to happen to him. Do your best to see if this girl he likes is worth it and give him the advice and feedback he needs, try to ignore the fact that you like him for a while and just be there for him like the close friend you are, he'll appreciate that and in case it doesnt end up working out with this girl, one thing he'll remember will be you and how you had his back there. He might even end up charmed by that and that could lead to him developing feelings for you again, who knows ahha