How do you know if a girl likes you. Or if she is just playing games or hard to get?

One way is to talk to her about her realitionship... most girls don't play games if they like you... she might be too scared you'll reject her if she tells you that she likes you

Some women twirl their hair around their finger. Some women make body contact with you or flirt with. Like for example a woman might rub her hip against yours or rub your arm or shoulder. Some women may gaze into your eyes.

Not all women play hard-to-get but some do. It's called a cat and mouse game to see if you can catch her.

https://www.askmehelpdesk.com/dating/im-love-best-friend-but-she-has-boyfriend-631106.html

Same girl? Must not of liked the answers you got, because she has a boyfriend. That puts you in the friend zone, so don't get carried away with the romance thing. There are many different degrees of like my friend, and I doubt if yours and hers are the same, given she has a boyfriend. I mean what would she do with two boyfriends besides be a playa, a liar, and cheater?