Sooo... there was this quite popular manga about this world where people died by falling in love with certain infected people. They were called vectors I believe?
Starts off with the girlfriend accidently killing herself to save her lover, just to prove he's not infected. Well. Guess how that turned out. Father never forgave the infected boyfriend who's currently on the run and joined the resistance/terrorist/vector-thing-group.

It was quite popular, I liked it a lot and now I can't remember the name. Couldn't find it with the immortal/s category either. Gah! Help me, pretty please?

Edit: Found it. Via the immortality tag. It's "Shinazu no Ryouken". Maybe delete this topic? 😀 thanks anyway!