Sounds like you kinda already know the answer

Jesus is not talking about using prayer to get what you want, but rather using prayer to discover what GOD wants, and aligning yourself to that. A faithful person would not pray for an impossibility for selfish reasons. If they pray for “the mountain to move”, it’s because God has led them to know that’s what God wants, so they pray for that to happen because that’s already what God is pointing to.
As for the girl: rather than pray she suddenly likes you, you should pray that God makes into the kind of person who is likable. Then, if she does like you, it’s for a good reason. And if she does not end up liking you, you know it wasn’t a good match up anyways. Trust me: you want the person who likes you to like you because you’re like Jesus.