You had a boyfriend who had been cheating behind your back and Sanemi who was your best friend and had feelings for you knew about it, he felt insanely pissed at your boyfriend but also really happy that he can finally claim you.

He pinned your wrist over your head to a wall in his room when you came over to his house for a visit as he spoke in a sultry tone

Sanemi: *I can keep a secret, can you~?

Sanemi then leaned in for a kiss, slowly deepening it :D