You need to disassociate story routes from relationships. If you're going to have a lot of love interests, you'll be creating a rabbit hole of dev time for yourself trying to create an entire route for each one. This is one of the cases where going sandbox will actually speed up development.
Example: Have Alex meet the male neighbor Day 1, help with boxes, then go home to find sister bought the girly outfits, then Day 2 he meets the female neighbor in the car, if the MC takes the bus he meets her on the street anyway, and the MC is invited to the party later on. Similarly, the Alley event happens whenever you manually choose the Alley.
What happens is that different dialogue and events changes when characters are first met. For instance, if the MC takes the bus he won't know the neighbors are siblings until the party.
But you end up saving dev time in the long run by using the party to establish the full cast.