The "Happy" hitmaker is thrilled that his fellow "Voice" mentors have found love with each other after both getting divorced last year, reported Femalefirst.
"It's poppin' off! It's so beautiful, because being there, I watched both of them go through a lot, you know. You hate to see your friends go through something so heavy, and it's kind of like a miracle, man - just watching that," Williams said on the "Today" show.
However, the singer was initially unaware that the duo had started a relationship.
"I had no idea.