When a suicidal boy discovers his girlfriend can only die if she falls in love, the two embark on a philosophical adventure to seek out the meaning of life.

I'm really confused -- If the girls dies when she falls in love, does that mean the boyfriend wants to prevent her from falling in love? With him, or someone else (and they're boyfriend and girlfriend and she is obviously not that into him seeing as she's living etc...) Very confusing scenario/ goal.

And what relevance does him being suicidal have on the plot? If he's suicidal, why would he care about 1. Her, and 2. Whether she lives OR dies?

... and seeking out the meaning of life is way too broad in the context of the story you are presenting, and as dpg said -- what does that actually look like cinematically?

You need to simplify things -- What is the ultimate goal of the boyfriend? Once that's established, what is the thing that stands in his way of getting it?

Best of luck.

Easy: 42...

"his girlfriend can only die if she falls in love" meaning the boy knows she'll end up dead if she falls in love. problem is why would the girl fall in love if she will the die in the first place? maybe the girl isn't really in love with the boy and "after" the two embark on a philosophical adventure to seek out the meaning of life that's the time the girl "really" fall in love and died... that's how I see it.