I feel like if I had a guarantee that after becoming a cuckold my girlfriend still loves me and we don't break up because of that I I would try that lifestyle. I could cope with not being the most alpha guy in her life and leave that to her bull, but I don't think we can cheat biology that easily. After months of emasculation you experience watching them there's no way things stay the same between you two. She will slowly lose respect for you as a man.
The more you read about these relationship the more you realize that almost all of them break up/divorce at some point. Which sucks because the realization of this fetish is probably one of the hottest things ever.