While she's with the male lead, she's very close to this other guy. The other guy loves her, but she only sees him as a close friend/brother. Though she constantly relies on the other guy more than the male lead without realizing she's hurting the male lead. The male lead feels inferior and hurt because of this. Like maybe she stands him up because she's with the other guy and loses track of time. Eventually she figures out what she was doing and feels guilty about it and lets go of the other guy to focus on the male lead.
