I like that he drops everything to come to her, even with a houseful of guests. I love how much they click and are finally realizing it. How she stood, staring out the window, even though she knew it would take some time for him to get there. The crinkle of the vinyl under her cheek. Love the little details.
That said, the scene needs... something. It's a little too pat to me, a little too... something. Maybe it needs a little humor, her blowing her snotty nose in a hanky and it grossing him out slightly, or a little sadness on Jay's behalf. After all, Adam is his best mate and Katie has just thrown a spanner into Adam's works. A little trepidation about how Adam feels, worry about the loss of the friendship, though Katie did worry about that before Jay got there. I know they're destined to be together, but they've had a lot of bumps along the way. Maybe a couple of minor ones in this scene might add to it.
As always, take what you like and ignore what you don't!
Man, I'm thick sometimes. Of course Jay would be apprehensive about how this will affect his friendship with Adam. Shoot, I even mentioned his feeling a flash of guilt for kissing Katie the day after he met her.