Her Boyfriend's Secret (2018)

A woman is strangled and left for dead.

A woman is discovered to be lifeless.

A woman is attacked in her home where she manages to wail a few swings of a bat on the attacker before getting away.

A comatose man is shown to have several lacerations and swelling on his face.

The killer boyfriend makes an attempt to kill a woman by strangling her, then shooting at her (and missing). She fights back, stabbing him in the gut with a box cutter before later landing him with a non-fatal gunshot.

Despite the killer boyfriend leading a double life two cities apart, only present on weekends and away on weekdays teaching college in another town with his clueless wife and infant child, he still manages to always be close-by the protagonists at any and every turn. Like he's some psychic teleporter.