Well if you aren't married and aren't tied legally or financially to one another, it's really just an open relationship.

Getting a bull, before you have talked to a therapist to help you manage expectations, is putting things in reverse order.

You really should be fully aware of what to expect before you do this. Have you had time to build a solid foundation? Is your communication 100% transparent and direct?

Maybe ask what you should do before seeking out a bull. What are the pitfalls that you don't see in cuck porn? What kind of work goes into making a relationship like that work? Techniques for dealing with jealousy? Boundaries and limits?

How well you secure your sexual health? Condoms? STI tests? Etc?

What are you going to do when she falls for her lover, who is older, more successful, charming, and can give her the things you can't as a 21 year old male? What do you do when a guy making $100k plus a year can make her question why she should settle down with you? Lots of younger women date older lovers. Women in their early 20's might just leave you for the guy who is financially secure and established and better at sex. What's your plan to keep that from being a problem?

If you've done these things, GREAT. But if you haven't, then do the WORK upfront to avoid tears and an end to your relationship.

I'm experienced in dating other mens wives. This isn't the jack off in front of the keyboard answer that wins lots of likes.

I hope that if you haven't considered everything and discussed it that you slow your roll and do the foundational relationship ground work first.

If you love each other, then there should be no rush.