It hits Michael now that this is the first time they're doing this in this place—his place. And that this is his place, truly. No one can come in without his permission. No one even knows he lives here except Lee and the landlord. Who is even going outside right now? They are not going to be interrupted.
It's a rush. He only has his undershirt on; her hands are close and warm. One of his legs slides between hers, and his kiss changes into something deeper. He's gotten better at doing this since they started. They both have.