How should I approach job materials for a lateral move entirely for two-body reasons? I am a tenure track assistant professor at a liberal arts college. I Iike my job quite a bit, but it is located in an impoverished, rural area. My partner works in the nearest large city, 2.5 hours away. I live there as well; the commute and the 2 nights a week I spend away from home are wearing on me. 

This year there is a job at a very similar (on paper) instituion less than an hour from my house and accessible by public transportation. It is the same size, in the same region, serves a similar student population, and the departments are of similar size and composition. Adding a small amount of complication is the fact that my current institution is (slightly) higher ranked. I don't put much stock in such lists, but I could see it rasing eyebrows. If it matters, both institutions are top 30. At the very least, my current administration cares a lot about such things.

To be clear, I am unconcerned about my tenure case; I am an outlier in terms of grant funding and publications, I have solid teaching reviews, and my school has an 80% tenure rate. I also work in a field where transitioning to industry would nearly certainly lead to higher salaries; my field has abundant job opportunities in my city. I don't think getting denied tenure is likely, and if it happened, I would be ok with that.

My question is simply how do I pitch my application, particularly the cover letter? It is hard to come up with a compelling narrative for why I would leave my current job for this one aside from the simple fact that I would love to be closer to home and continue my work in a similar institution. I am not certain if addressing 2 body issues directly is a good idea. My partner is happily employed; they are not looking for work from this school.

Edited to add: I worry that by mentioning my personal issues, the committee will be disfavorably inclined, as @strongbad has indicated below. That is, they get hundreds of applications from qualified people, they do not care about my personal life. However, excluding that detail might make them think there is some difficulty that doesn't appear in my materials.
I would tell it like it is:  You have a two-body problem and a 2.5-hour commute that you need to solve.  As soon as you say those words, everyone will understand.