The Scream star is dating McLarty, who split from adult filmmaker Joe Francis last November (10) just seven weeks after they married.
And Arquette insists he's serious about the TV reporter, telling shock jock Howard Stern he has fallen in love.
When asked by the radio host if he's happy and in love, he replies, ""Yeah, I am... It's not a rebound.""
Stern then pressed him further by questioning whether he would move back in with Cox following their separation last summer (10), prompting Arquette to state simply, ""No.""
The actor then revealed Cox was devastated when he told her about his new relationship, recalling, ""She was sad. We were both sad. We both cried.""
After breaking up with Cox, Arquette enjoyed a fling with waitress Jasmine Waltz. He also went public with that romance during a live on-air phone chat with Stern last year (10).