Complex sentence: Nick, however, continues to rebuff her advances, and Adrian's actions become destructive--she defaces a car he's restored and erases his computer discs--yet he's unable to convince Cliff and Liv of what's going on.
Split into simpler sentences: Nick, however, continues to rebuff her advances, and Adrian's actions become destructive. She defaces a car he's restored and erases his computer discs, yet he's unable to convince Cliff and Liv of what's going on.