My alternate idea is a bit longer:
Two introverted neighbors live out their unrequited love for each other in flashes of fantasy until one attempts suicide and takes it to the another level.
Think Ruby Sparks meets 500 days of Summer with a twisted ending.
As a reader, without your synopsis, I would have been lost. Start with your “neighbors” logline, then show not tell “takes it to another level”.
Once you have this, post it here for the community or me to provide feedback.
Interesting start, keep going!