The vacancy in your heart doesn't connotes that nobody is seeking for the job of servicing your feelings, but because the employee must first have all the necessary credentials needed for the job.
credential
date
give-it-to-me
heart-for-sale
heart-job
i-give-it-to-you
life-for-rent
man-enough
mrs-right
my-heart
only-you
stamina
vacancy
love-affair
test
real-love
romance
bravery
you
crush
job
mr-right
examination
i-love-you
strength
brains
first-love
befriend
dating
employee
friendship
affair
weakness
temporary
hard
real
heart
responsibility
satisfaction
approach
be-my-friend