Not that Robin had had a particular idea of what Much might say, but that surprised him, and he burst out laughing. "Why does everyone seem to think I need her permission, or-- her blessing? That sounds like she's had to smile her approval on what I do." It was not so much that he thought he would just come and go as he pleased; it would not be fair if either of them did so. But he did not need permission.
His friend's words did not seem to be anything more than just a tease, and Robin hoped that was the case. While the tension between the two of them was something he planned to address tonight, he wanted to converse about other things first.
Much's love life, on the other hand, was a perfect way to go. And that was the perfect opening for that particular subject. "Besides, she's out tonight, herself, with your girlfriend."