"screw it" they were both about to do something they didn't want btw, they're so gay, Jopper and Jancy didn't hesitate to kiss each other because they're actually in love with each other, Mike doesn't love El romantically
HE'S SO GAY 😭, Mike forced himself to do something he didn't actually wanna do because people forced this idea in his mind that he liked El just because he was nice to her, he's victim of heteronormativity and forced conformity
he didn't hesitate to hold Will's hand and to squeeze it
More about the scripts here
plus in the Jopper first kiss script it says "finally" instead of whatever this was because they actually wanted to kiss each other, Mike didn't actually want to kiss El