Hwanbulbulga Alpha

Jae-won Choi, is an omega who enjoyed a free-spirited study abroad life with rabbit-like alphas. When he returned to Korea after being tricked by his father, what was waiting for him was...a marriage to his childhood friend Yang Jun-hee?!
Unlike when he was young, Jae-won ends up getting married because Jun-hee appears as his ideal type. Jun-hee says he made a promise to Jae-won when they were younger, but Jae-won doesn't remember this at all...
A sexy romantic comedy about Jae-won, who is a simple-minded jerk, and Jun-hee, who pretends to be a gentle sheep for Jae-won!

(Source: Bomtoon, translated and edited)