In OMG! OH MY GIRL, college student Guy (Wongravee Nateetorn) has a crush on June (Plearnpichaya Komalarajun) from afar. His best friend has the nerve to declare his feelings, and June begins an embattled, off-and-on romance. Guy observes but never can insert himself at the right moment to begin his own romantic relationship with June. Thus begins the wash-rinse-repeat cycle of Guy's frustrated love. He and June do become friends, but they spar rather than mesh, and he remains in her friend zone as she takes up with a new partner, Pete (Pachara Chirathivat), the rich, handsome guitarist and a notoriously nice person. Only in a drunken video does Guy finally have the nerve to tell June outright how he's pined for her, but he sends it in the middle of the night, and, far too sleepy, she doesn't watch it through to his avowal of affection. Years later, she learns that he'd declared his love, but somehow, it's, again, the wrong timing. She's now engaged, but unhappy enough to meet with Guy anyway, only in order to tell him she'll never see him again. Will the two star-crossed admirers ever get together?
