Advice on moving onto dating .

Well where to start my wife and I have started up with a single guy as a threesome its only been going two months and in that time we have meet twice a month all together . In our time together theres a lot of sex between my wife and lover . I have the ideal situation of fluffing and clean up really . Deep down I feel the desire to move deeper into a cuckold relationship . Which I would ideally see as the two of them dating and meeting together as a couple . I’ve raised the subject with her expressing my wishes , but she is reluctant to meet as a two and strongly feels she doesn’t want me to be left out .This I can quite understand but have no fears or angst about this happening , as I certainly wouldn’t feel isolated. I’ve also expressed this wish with her lover and he understands where I’m coming from. So what I’m really asking for is advice to move things forward down this route .