as of her getting together with pink hair, she plays around a little too much for me
They are not together though. The translation is a bit rough sometimes, but Yeon Woo definitely said, that she didn't want to date her. They are just sex friends, or hookup partners. With no strings attached. Ji-ho is hopes to date her but that's about it.
And she knows (or she thinks she knows), that she's taking advantage of her - very
very straight, and
definitely not gay for her, what are you talking about? - best friend's, Woo-hui's goodwill, when she asks to touch her
"bust", and she even feels guilty later. So it's not like she deliberately plays around, she just can't help herself.