I'm not sure what an "adequate Path B" would be. Yes, you would miss
sexual content with girls if you avoided their paths. But that's the very point of giving you those choices. What else would you miss? Not
story progression. That is independent of what happens sexually.
Do you mean having sex with Girl A INSTEAD OF Girl B? That IS what non-harem stories do, not this game. Try this though: make a playthrough for every girl. Concentrate on one girl for each route, ignoring all others. There - you have created a non-harem game out of this one.
But, no, you're not going to get situations where if you romance Girl A, she marries you, if you don't, she joins a convent or commits suicide or kills your puppy or some other path that completely changes the story. I say, thank goodness!
Forgive me if I am misunderstanding you, but you seem to be boiling everything down to what happens with potential LIs, which gives disservice to the actual game, which is
almost worth playing without any sex.
As to whether you feel uncomfortable having the MC tell different girls that he is madly in love with them, I can empathize with that view, since I feel it myself in many games, especially when I try to make a harem game out of one that's not one.
But, I haven't had that feeling thus far in this game. But, maybe that's just me not being sensitive enough.