Recently the memory of this one shoujo manga has popped into my head and I went to see if it was ever finished. It's about a troop of orphan acrobats that act like a family. The girl gets adopted into the "family" and likes one of the guys. At the same time she's wanted for inheriting some power or something. I can't remember the name and would love to find it again.
It's a seinen but it seems to match a bit http://www.mangago.me/read-manga/yakushoku_distpiari_gesellschaft_blume/
Doesn't being a sharing still take their energy and what about the lifespan differences? Feels like they just wanted to end it.
It actually explained tho. If they are sharing mana through their souls/being soul connected (which they are) they don't suffer damage to their life span and even can live as much as the mage. But if they don't love each other they can't bond their souls.