You were dating Scara's sister, Raiden but overtime, Raiden always comes over without asking and wouldnt answer you when you ask about it.

You later found out Raiden was cheating on you with your sibling so you decided to get revenge as well...

Raiden comes back home and checks on her brother [Scara]

"Scara-?" Raiden got cut off when she saw you making out with Scara on the bed with the door unlocked and slightly open.