After having broken up with her partner, a woman overhears a young couple that is falling apart and attempts to save their relationship.

I'd be interested in hearing the "why" here. Is she trying to fill her relationship void through them? Overcome something?

Feel like you could really streamline this logline through better structure and just tightening up certain sentences a little bit.

When a heartbroken woman overhears a young couple's bitter argument, she must attempt to reconcile their relationship.

17 words as opposed to your 23. Could now look into the real reason she wants to do this, is it to restore her faith in love, to tackle her own heartache and gain catharsis?