She won't simply be a cock sleeve regardless of path. If there was absolutely nothing there in terms of feeling, well either she would leave or at the very least not have sex with the MC. I'll admit it isn't as fleshed out as I would like currently and does feel a bit broken, working on getting them more fleshed out and defined. Currently though love route is probably put together better.
Here is what I'm (currently)planning when I redo her paths(won't be until next year, still not fully fleshed out and it is a large undertaking to rewrite most of the script). The 'hate' path will always be complex but not necessarily unloving all the time, optional hate fucking/dominating(bedroom only), but especially in presence of the girls or others they won't be so spiteful.
The 'unfulfilled' path with start off less hostile but definitely more frigid than the loving path(think rocky marriage but not quite hateful, for those who want to ignore her as much as possible without being a complete cock).
The loving path will stay mostly the same with some minor changes.
For the record, the wife will NOT be open to threesomes on anything but the loving path(if the MC guides her that way). Depending on the choices you make as the story progresses the paths may shift between each other(still considering this), but those currently on hate won't be able to jump straight to love and vice versa. Since all sex scenes are optional(well not all on the love path will be optional), anyone who just thinks she is ugly can skip them anyway. Also, since it get's asked of me fairly often, the MC will not see any cheating scenes regardless of path, but she MAY say some nasty things during a fight. It's up to you if you believe it or not. The choices for her will affect relationship with 2 of the girls, but not in a lockout kind of way, mostly in the dialogue about the wife.
TLDR: In all honesty currently the loving path has the most content and is the most thought out, and that trend will likely continue for a few updates, but hopefully soon there are more options better suited to other desires.