I suspect calling a man who fucks your wife a Bull, or a lover or other names is personal choice.
My cuckoldress has never liked the term Bull, as she has said, she is not a Cow! we come from farmering stock ourselves. Therefore to us a bull is simply a means to an end and an emotionless act.
Our prefered has always been lover, or Sir dependant on what he is into.
She has fallen in love with two of her lovers over the years, its becomes very risky and complicated i will add not something i consider desirable. My view has always been, Yes i give her to him to fuck and pleasure, but dont want to loose her as my wife and my best friend.
There are hundreds of ways to explore humiliation, we have tried so many. The ultimate has to be her being fertilised by her lover and his baby growing inside her for the Cuck to bring up as his own ......, or the inclusion of him the biological father in doing so. That bring with it moral issues though and real complications.
In my view, given that the OP has not fucked his wife for 3 years and yet gets fucked in the ass by her with a dildo he is quite fortunate.
My cuckoldress chose the path of semi feminising me, thus the demasculinization of her husband, a man with a large sex drive and kinky mind, the sex drive no longer needed the kink definately.
So SHE chose to make her Alpha, dominant masculine male more sexually feminine as discribed elsewhere, a wearer of female underwear and clothing (female tight jeans) collar, cage, a man with pink toe nails etc. A man who sleeps, locked, collared in pink, silky PJs.
For me one of the ultimate regular things we have done is for her to ask me to swop my knickers for hers, ones that are wet with her juices and his cum, so it dries and sticks around my locked balls and sticks to my hairs. Occasionally i have then developed a wet spot in my tight light blue female jeans, We have done this even in a restaurant awaiting a meal, him sat by her side, stroking her leg to orgasm again, he knowing and that i am locked and caged too.
Three professional people like any others but not quite like most.
Even after all this time i still find this an act of kinky sexual sub, especially when we go out me in tight female jeans sometimes a garter belt with these sticky knickers on. As she has said, she likes this and in accept her knickers it demonstrates my sexual sub to her and in a way to him too and demonstrates my status as her loving cuck husband.
I did once raise the subject of castration but she wouldnt allow this, therefore i retain wants, desires but caged over many years, locked i am unable to act on these.
Therefore i now enjoy mental stimulation rather than physical. It is miles better too, much more electric, stimulating and kinky.
One kink that i have failed on, and its rare ive failed on anything ive thought of, is for her to take a lover who i have never and will never meet, she simply refuses to do this as to her this senario would remove my involvement which she wouldnt like and she likes being mounted as she looks me in the eye as he pushes into her.
She has though met her lovers alone many, many times but with my permission but that in her mind is different, yet still very stimulating and kinky for us all.