Thor hadn't wanted to believe that Loki would do anything with that Pyro person that crossed the line. Granted, it would be her right if she so pleased. They'd never set boundaries, and neither of them were very good with that term anyway. Still, Thor didn't think Loki would do that; something that would cause him actual pain.
Stabbings, yelling at each other, fighting, mindless bickering, thunderstorms, one-upping, all of that was regular behavior that they were used to and none of it really hurt (give or take the stabbing). But Thor was pretty sure Loki knew that if she did something with someone else -- the sort of something that they privately engaged in, that would hurt him in a way that would be difficult to come back from. And though he knew Loki was furious with him, he didn't think she'd do that.
A small smile pulled at the edge of his lips when Loki confirmed she did not hate him. He lifted a hand to touch the side of her face. "Then come closer," he beckoned in a low voice. "For it has been far too long since you've been near."