The Good Charlotte rocker and actress Diaz sparked rumours of a new romance when they were spotted spending time together in May (14), and reports suggested they had been introduced by mutual friend Richie.
Now the fashion designer, who is married to Benji's twin brother Joel, has opened up about her matchmaking project.
During an appearance on U.S. chat show Watch What Happens Live on Tuesday (08Jul14), Richie was asked if she approved of the new couple's budding romance, to which she replied, "I approve of anything that's going to make Benji happy. I am a devoted sister-in-law. I'm happy for anyone who is happy, and I want everyone to be surrounded with love."
When questioned if she was the one who officially set Madden and Diaz up, Richie admitted, "Yes. I'm going to take responsibility for everything!"
Diaz recently took their relationship to the next level by introducing the rocker to her whole family during a reunion in Florida over America's Independence Day holiday weekend (04-06Jul14).