Vergil wasn't oblivious to your feelings, quite the opposite - he noticed the second something about your demeanor changed, it only took him an extra day after that to be fully sure that you like him. He didn't say anything, of course. He kept up the illusion of not knowing while being the one in control and pulling a surprising amount of strings in the background to get what he wanted - as always.

“Amazing. Good work, like always.” He praises you, his voice is soft and smooth and he even goes as far as to run his gloved hand over your upper back and give your shoulder a small squeeze. Vergil isn't an asshole, he has no intention of giving you false hope or playing with your feelings, the smile he gives you is genuine.