During Tuesday's episode of The Tonight Show Starring Jimmy Fallon, 44-year-old Ventimiglia gushed about 37-year-old Moore, who has played Rebecca Pearson since the show began in 2016.
"Right before the show premiered, we were in New York for the upfronts... and everybody was kind of milling about and Mandy and I were just kind of off to the side by ourselves and we just kind of raised our glasses to one another," he recalled. "We almost took vows with one another where it was like, 'Hey, I promise to always communicate. I promise to not be happy until you're happy. I will always look out for you.' And we have stayed very true to what we said in the beginning."
But Ventimiglia didn't stop there. The longtime actor shared nothing but admiration for Moore, adding, "I've got to say she has been probably in my 26 years in front of the camera, the best partner I've ever had -- her commitment, her dedication, her growth as an artist. The audience, you guys get to watch the show in its entirety. I get to sit there in front of her, or stand in front of her, or lay in a bed next to her and watch front row what she does and how impactful it is, the work is to her. And I've only seen it grown. So, it's been a pleasure to be her TV husband for six years. At the same time, closing this chapter, I'm very excited to see what Mandy does next because she's such a force."
As for what fans can expect from the show's final season, ET's Denny Directo spoke to the cast last month. No surprise, viewers will need to have their tissue boxes close by.
"I don't think there's any preparation. Just know it's coming, like, know that you're probably gonna get emotional, you're gonna be upset about it," Ventimiglia told ET.
Moore echoed the sentiment, adding, "Lots of tears, but good tears, like, cathartic tears. Tears that show you you're alive and you're human and you feel things. It's pushing a bruise in a good way. You're like, 'Oh, I feel it.'"