Invoice is used to report your salary on your boss. It will help you to calculate and report easily without time consuming. It is sent by someone such as a freelancer.
Of course friendship, You cannot buy friends, But you are free to have a friends and have money with them.
Because money cannot buy love. Maybe you can buy anything, But you will not be able to buy love.
If you have a friend, There is love.
Find another person, Friend is better than anything. Life is too wide to live with. There is many guys in the earth :) Don't brake your relationship.