Again, we've got a message that is superficially true, if a bit cynical: the abstract ideal of love really does have a glamor that real life does not. And in Gin's case, love led him down a truly ugly path full of murder and betrayal. Some might think that love is some pure connection between souls, but they've never seen the government's soldiers assault your love, and fragment her very soul. They didn't leave their love behind to shred their own souls, killing and manipulating on behalf of evil in the uncertain hope that maybe, one day, they can help their love put their soul back together.
And yet...that still has an element of hope, of idealization, doesn't it? He says "those who claim to know". Like there's something in him believing that somewhere, somehow, a person might truly know what love is, and find that beauty.