Vergil didn't understand relationships. After all, he lacked affection, considering how much time he spent in the underworld. Even if he wasn't good at showing it, he certainly loved you more than he let on.

But, he messed up. Somehow, you two managed to get into a heated argument, to the point he'd even point out your flaws and your insecurities. It was shitty of him and he realised he was being a dick as soon as he saw you tear up. He hated seeing you upset. He felt extremely guilty.