Cuckolding is best when you have an emotional connection with the provider, that way you get the full emotional experience (roller coaster) of watching your girlfriend with another guy.  And when he leaves and you "reclaim" her, the sex is some of the best you will ever have.  The best sex I ever had was a MFM with my ATF who I had a deep and long standing mutual connection with in Chicago.  Watching her kiss him, blow him, fuck him, and jack him off on her breasts was the hottest thing ever.  Our one-on-one sex after that was exceptional, especially when she said she was still my girl.  Without the emotional connection, it's just you watching another girl get laid which, while it is hot, is not an authentic cuckolding experience, IMHO.