I agree with you there. I've seen the two being interviewed as a couple on TV during the Dubya administration, and when they were talking Bush policies, they would argue and disagree. But as soon as their children were mentioned, their eyes both list up and they were lovey dovey. Seeing James make googlie eyes at Mary was sort of creepy, but she loved it, and I do believe they both love each other.
Here's a 2014 interview: https://www.youtube.com/watch?v=G1HrUulPtNM
None of us know them; however, it's a pretty good assumption, that they have common interests other than politics and that they are VERY lucky to have found and fallen in love with each other. They've been married for a long time and there has NEVER, to my knowledge, been anything ever said or written about them, to disprove my observations from afar.
I remember when they got married and Rush went to the wedding. He was very happy for them both and even said that old Snakehead was very very nice to him.