People respond to praise. People thrive on appreciation and attention. We know this. We practice it freely with pets and kids. We lavish praise when we're smitten with a new love interest. And although we know that it works and makes others feel good, we often neglect this behavior when in a long term relationship
"If I praise them all the time, it won’t mean much"
"I shouldn't have to praise them, they should just do it because it needs to be done"
"I shouldn't have to praise them, they know I love them."
"I shouldn’t ask for praise, I should be an adult with no needs"
On a behavioral level, praise reinforces behaviors. Want your partner to take out the trash? Ask and then say "thank you". Bonus points for expanding on a "thank you" with feedback on what the behavior shows you about the person's character, how it helps you, or how it makes you happy (thank you. That was so thoughtful of you/ it saved me some time so I could get other things done/ it makes me feel special").
On an attachment level, praise demonstrates appreciation and respect and reassures the other person that they matter. Attachment takes work and maintenance and consistent praise and gratitude helps build that bond and create a sense of safety and connection. This is vital for the health of the relationship. And all it takes is a moment.