I'm looking for a manga I read a long time ago and want to reread but I can't remember the name. It's about two boys who live in a fantasy world where to live they need to exchange essence or magic through a kiss. One is a receiver of the essence/magic and the other is the provider and they would both die without the other. Everyone in the world is divided into receivers and providers. Heterosexual couples are the norm, but the parents of one of the boys is also a homosexual couple. Please help me find this manga!!!!

Sounds like this one?
Shinkuu Yuusetsu