I can give you some romance manga suggestions: Hot Blooded Woman (it's korean, but don't worry, it's interesting), Mars, Cat Street, Paradise Kiss.
In the case of Paradise Kiss, you may check the anime directly. Oh yes, Nana too. But go directly for the anime (if you read the manga you can't hear the music !). The anime doesn't end the story, which follows in the manga (and it's still not over).
Ok, so I might have tricked you on some of those with regards to having separations/deaths, but you won't know until you read them !
