Today was the first time you've seen him preach?! I'd assumed that was an early "date," Klara Jane, given that's who he is.
Having grown up in the church and wanted (long ago) to be a preacher myself, I think I'd say that most preaching is performative without being artificial. As a professor, I "perform" in my classes but it's not an act or an alternative role, just my attempt to communicate as clearly as possible--through humor, seriousness, exaggeration, rhetoric, eloquence, movement--exactly what I want the students to learn. I'd put preaching in a very similar category.
I'd also say that most preaching is one-directional. No one interrupts a sermon to ask a question or dispute a point or offer an alternative reading. (I do experience that in my classes.) The very qualities that make him a good preacher--conviction, certainty, delivery--may be maladaptive to a loving relationship, which requires listening, compromise, apology, change.
That doesn't mean he can't exercise different qualities in a relationship from those he uses in the pulpit. Of course he can: we all do that sort of thing. Speaking personally, though, when I began to realize that many of my qualities were bad for relationships, like my defensiveness, my logic, my skill in argument, I began to regard those qualities as "bad." I found it very freeing when my counselor noted that those qualities had served me well in my profession, even though they were "maladaptive" in a loving relationship. I just needed to realize when they were serving a good purpose and when they were not, and it made my love life much better (though, sadly, it did not last, but that's another story).
All best to you! I'm rooting for you, Klara Jane.