There are too many factors here that make recommendations difficult and as you probably know, women are prickly to deal with, very picky and very hard to understand.
So what a woman would like and what your wife would like makes things very hard, especially with no knowledge of your wife.
Plots are a common theme with women, this is why movies with female dramas are so popular.
As a soft suggestion, I'd say look at the PureTaboo series, which involve relationships, sometimes familial ones (roleplay), plus the Deeper series, Erika Lust Films, Xconfessions (a VERY wide range of themes and styles with them so check first - Xconfessions is from Erika Lust), MissaX, perhaps there are some from KellyMadison/TeenFidelity/PornFidelity.
The problem I think you will find is that identifying this niche is hard, because most porn is focused on men (who just want to jerk off and have no need for stories/plots etc and certainly little to no dialog), plus there's a good sized portion of Lesbian stuff and all the other stuff.
Entering "drama" or "plot" in the search field will help but its not a black and white thing. "Popular with women" is also a tag you can search for as I have seen this often in the list of tags for movies that may fit what your wife wants to see.
I think though once you do find a bunch of movies that you/your wife likes, the people performing in those movies can be put on list and then you can see what else they have done/are doing as people who appear in drama/plot based scenes continue to do them. Plus if you find a studio that ticks your boxes, then you can follow them too.