"You think something's happened to him." It's not a question. If Pepper thinks something happened to Tony, then he believes her. After all, Pepper knows Tony just as well as Rhodey himself does. They might be a little overprotective at times, but there were reasons for that.

And, honestly, it's not like Tony to not respond to Pepper in any way. Not for two whole days. It's worrying enough that he doesn't blame her for wanting to find him. It could be nothing. It could be Afghanistan all over again. If it is nothing, Pepper going alone wouldn't be a problem. But if it's not...

"I can be there in thirty minutes. If we're going to be "married", we might as well go together."