That's just the unfortunate balance of genders in our society. Men don't get complimented unless they're really extraordinary (either in looks, humor, etc).

How can I figure it out unless I ask?

Reflection coupled with trial and error. Reflection is very important in all aspects of life. Spend time thinking about each day, what happened, how you behaved, how that impacted others, etc etc. With this girl, think about the times you've spend together, what you've said, how she's reacted. Try to work out what you did that was good, and what was bad.

In the end though, you may have done nothing wrong. You might simply not be her type. You cannot expect everyone to potentially like you if you play your cards right.

Generally speaking, every partner I've ever had, we hit it off straight away. I knew she liked me, she knew I liked her. The concept of 'making someone like you' is baffling to me, and while I'm sure it's happened to some people, I think it's pretty rare.

Why are people so concerned about not hurting my feelings that they won't give me the advice I need and ask for?

People generally don't like hurting the feelings of others, especially people they consider friends.

If you really want to know, it might be acceptable to say to your friend who rejected you; "Hey, I'm sorry for how I acted before, but I'm feeling lonely and having a hard time meeting anyone who seems interested in me. I'd really appreciate it if maybe you could give me some pointers, maybe I'm doing something that turns people away? It's fine if you're not comfortable to answer." If you do this, I'd suggest doing it via text message, as it's less confronting to her, and makes it easier to say no.