My friend's rudeness and lack of manners is really annoying me.?

Well one of my friends has a huge lack of manners and is very rude. She's very nice to her friends but when it comes to adults she gets snarky. But also lacks manners in everyday life. She NEVER has money to pay for her own things when we want to go to the movies or when we go to the mall it's like she expects someone else to pay for her. She says she "doesn't want to impose" but she expects it. You can tell. And she never thanks anyone when she leaves a house, or after a ride, or when someone pays for her food, movie ticket, etc. And when I confront her about it she'll say, "I'm sorry but I had a lot on my mind. Which is caused by an infatuation that she has with this boy that she loves and can't get over him. I've been in love with my best friend (who is a boy, yes) for 6 years so I feel that she shouldn't let her control her life. I love him but I've learned it's not going to happen so why worry about it. Help?