“I want to tell her to leave him.”
Here leave means to end a relationship with a partner or spouse, rather than simply move away physically. Tina wants to tell her friend to break up with him.
B1-48 / CEFR B1 / EPISODE 48
Sharing a concern and hearing the other side
SceneTina is visiting Frank. She's worried about a friend's boyfriend and wants to talk to her about him.

WORDS & CONTEXT
Here leave means to end a relationship with a partner or spouse, rather than simply move away physically. Tina wants to tell her friend to break up with him.
Hear someone's side means to listen to their perspective in a disagreement. Side represents a position or viewpoint. Hear both sides asks for each party's account. Tina plans to explain her worries, then listen to her friend.