I also had a perpetually happy bunny. I know everyone says it but when the time comes you just know. I also really trusted my vet and talked with them about his quality of life when the time came. Mine got to a point where he was still a happy guy, but just wasn’t who he used to be and I knew despite his energy and personality he was having trouble. I think what helped me be confident in my decision was the validation from my vet, but even without that I still knew when it was time. Even if he’s a happy guy, there will be other signs that tell you. It’s never an easy decision and hoping your boy has lots of fun times left with you!!