He can understand that answer, at least. Of any she might have given, it's by far the least likely to cause the argument she fears. It won't make him entirely forgive it, but it at least doesn't immediately set him wanting to yell at her about it all over again.

"It's unfortunate you and I weren't correctly aligned." A dangerous admission, perhaps, when it both indicates just how much more comfortable he still is with her than with others here, and leaves open the unasked question of whether she would have picked him over Luke if she could have. But if Rey had been an option, he wouldn't be so stubbornly resisting the idea of tethering at all. He doubts there's anything that extra link could add to their connection that doesn't already exist between them.