Ehhh, that's not entirely true, the game is clearly pushing players to pursue multiple LIs, but the thing is it also punishes players for cheating and getting caught... it sounds contradictory, but the game is really all about the drama of the various situations you can get into.
Solo PTs kind of avoid the drama, which is the point of the game, soooo no, I wouldn't say "the game is geared at this point to have only one LI", not at all.
Of course you CAN do solo PTs for each LI, but chances are you'll miss a lot of content, like for Valeria, for whom the optimal path would seem to also be on Alexis' & Nikki's paths as to get the most out of her content.... or how you need to be on Layla's path to get to Elena... in fact, there's no solo Elena path at all.