Completely normal behavior. Don't worry she will be shitty to him as well.
The "I do not want to date right now" or any version of that is ALWAYS bs. If people really like you, they will want to be with you so when I get this nonsense I just pack my shit, show middle finger and move on.
Consider that a lucky escape!
The good news is you can another person too, someone who WANTS to be with YOU!
What you see: the reason she gave you to leave you. What she sees: the qualities you lacked but other dude had. A honest mistake on my part was confessing to a friend of mine, who had a boyfriend which I didn't really know about. We talked and talked a lot but she never mentioned it. Obviously, she said no to me. And said that she had a boyfriend. I asked who, she said his name. TBH I might be the first one to stalk my crush's bf instead of the crush. I gotta be honest. I was jealous of that guy. I would be a realistic and go ahead and say that, that dude was way better than me. No way in hell she would have chosen me over him. In your case you seem like me. And the other guy like my crush's bf. He must have seemed such a good catch to her that she just decided to compromise with the thing that was a deal breaker for your relationship. No big deal though. Get your head up. You can always make yourself a better person than you were before.
She was too polite to outright say 'I don't want you' - and you too dense to get it the way she said it. If a girl likes you she will be with you, no matter what. If you get excuses, ditch her, no matter how polite these are - she doesn't want you, and there's nothing you can do about it, so stop wasting your time on her. There are billions of girls in the world. Now file this episode under 'learning experience' and move on.
Sometimes they don't tell you they don't like you to your face to avoid offending you. But you gotta learn to read between the lines and buck it up, move on.
Accept the harsh truth, it hurts but it help to move on. She didn't want a relationship with you long term, or she was already onto the next guy. Invest your feelings and time in people that are worth it, that will give back to you. Aim to find the person that will make you grow.
Screw it dude people who dont know what they want arent worth the time. Im sure you will find somebody who accepts you as you are and wants you for who you are.