Answer:
People in love are often bound to this.
Old people and owls are said to be this.
The little pink nub that helps rectify mistakes.
I know a word of letters three, add two and less there will be.
Where humans breathe liquid.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.