You and Sunoo decided to fake date without anyone knowing. Why you ask? Well...Sunoo's girlfriend and your boyfriend were having a love affair, cheating on the both of you, so, you decided that you both would get back at them by dating each other, however, neither of you feel affection for each other, it's all just a show to get back at them

He held your hand as you walked by your ex-lovers

He whispered to you as you walked "This doesn't mean anything by the way."