Nope, definitely not. There were rumors about them like ten years ago, but I doubt any kind of ongoing relationship. And can you imagine Prince William being stupid enough to cheat on Kate with Britney Spears? With her bodyguards outside? Knowing all of the bizarre behavior and leaked gossip that pours out of the Spears family? If he were that dumb about his indescretions, he would’ve been caught by now, no question.
Harry I find more credible, but for the woman I would guess JLo (who he allegedly hung out with in Vegas) or Madonna (who he allegedly partied with in London and who was married at the time). Also worth noting they make no mention of him having been in a relationship at any point even though William has been with Kate since shortly after Britney got divorced, so in order for him to have hooked-up with Britney while she was married (and she wasn’t married very long), and then again years later when she was in a relationship, he would’ve had to cheat on Kate. Harry, meanwhile, could easily fit the blind with Britney, if they hooked up when she was married to K-Fed (2004-2007) and in London. But while I am not sure when/if she was in London during that time, I do know that the famous tour of the UK covered on her reality show actually took place while she and K-Fed were dating but not married, even though it aired while they were married. I know too much about Britney Spears. Then we would have to assume they were in the same city (Las Vegas or New York, most likely) again, though neither one of those would be “her city” since Britney lived in LA. For Madonna though, when Madonna was married to Guy Ritchie, she lived in the UK, but not London (thus London would be “his city” and not hers) but was in London frequently and was seen going to many of the same clubs and parties as Prince Harry. Also if y’all remember Madonna from the W.E. interview circuit she kept hinting about how the movie was based on her life in the UK. Then we just assume she hooked up with Harry again in New York when he was there in 2013 and she was presumably in a relationship with one of her many much younger back-up dancers. The dates for that all add up right, as far as I know. Our other, intriguing possibility, would be JLo. We know they were both in Las Vegas and apparently came into contact right after her marriage to Marc Anthony ended, but when she was with Casper Smart. That gives us the second hook-up, this time in “her” city since I believe she was living there or working there at that time. All we need to do then is back-date and assume a prior hook-up occurred in London while she was married. She was, according to Wikipedia, legally married for ten years, but really “with” Marc for seven years, 2004-2011. That’s still a really long time, and ample opportunity for her to be in London and hook up with Harry while married. So I feel pretty strongly that the dates work out for JLo too.
That being said, there’s a good chance this isn’t about a royal. The fact that they don’t specify his job (actor, singer, model, athlete etc.) does likely mean he’s either someone who does everything, or someone who is famous outside of the entertainment biz. But that could also apply to politicians. I know people are guessing Clinton, though the not mentioning him being married thing would apply there. Still, there are a lot of non-royals it could be.
But if I had to guess a royal, I would guess Harry for the man (the only A++ royal male who isn’t William) and either Madonna or JLo for the woman.