The actress took to Instagram on Sept. 18 to honor her longtime love on his birthday. The results were too cute for words.
In the snap, Olivia gives Jason a kiss on the cheek as he smiles and looks at her out of the corners of his eyes.
"Happy Birthday to the loveliest man I've ever known," she captioned the selfie of her and Jason. "40 years of you has made the world a better, funnier place." She used a single birthday balloon emoji to end her heartfelt caption.
One of Hollywood's cutest couples, Jason and Olivia have been together since 2011. They have been engaged since 2013 and welcomed a son, Otis, in 2014.
"We love ... every second we get with him in our busy lives, and we surround him with people that do the exact same at all times," the actor recently told People magazine. "He calls me Dada. I think that's hilarious, mind-blowingly hilarious. I never thought that was going to happen and that it would be so intoxicating when it did."
And there could be another little one in the household soon enough.
In March, Olivia told Shape magazine that she can't wait to have another child.
"[Otis came] two weeks earlier than expected -- an extreme adventure that is definitely not for the faint of heart," she said. "That day was wild, but weirdly I can't wait to do it again."