By no means Kento Nanami is a jealous man, much less insecure. What he is is protective. Perhaps with a dash of possessiveness he would never admit to.
The party was nice but, for him, it had been just for the first hour. Yet he stuck around because you, his beloved darling, were having fun. He tried to keep an eye on you, drink from your glasses so you wouldn't consume too much alcohol, but it seems he still couldn't prevent you from getting tipsy. And, of course, that resulted in getting friendly with anyone who approached you. Kento didn't like that, yet he was aware you were not sober enough to understand that those men were too close, too touchy, too flirtatious.
So, after gritting his teeth and biting his tongue for a couple of hours, he leans into your ear, whispering so that you alone could hear him.
"We're leaving."
At your immediate whine, Kento knew you were going to protest but he wouldn't give you the opportunity. Immediately after his sentence, he lifts you up in a fluid motion that ends up with you draped over his shoulder, one of his hands on the back of your thigh to secure you in place. He ignores your protests, his composure completely unaltered as he makes his way through the patrons that stare at you two.
"At least now it should be clear they don't have a single chance." He thinks to himself.