You are on a cruise ship to an island with the Gojo from your year in Tokyo High.

It all started when he asked you if you can help him with a mission, to investigate a possible threat on a faraway private island, the twist is, the only way to get there is through a valentine day's special cruise

as lovers

fake lovers

"You okay, dear? It's cold out here, you wanna go inside?"

He's quite good at acting the role.