Singer Carl Thomas Warns Ne-Yo About 3-Way Relationships

Ne-Yo is happily living his truth as a non-monogamous man -- but his R&B OG Carl Thomas is forewarning him that 2 heads aren't always better than one!!!

The "Because Of You" singer was turning heads in L.A. yesterday when TMZ Hip Hop caught him at The Grove with both of his girlfriends -- and, though he told us he's not looking to get hitched anytime soon, he IS loving the lifestyle!!!

Carl's a little older than Ne-Yo but added his own 2 cents to the convo after The Shade Room reposted our clip -- he says he once entertained a throuple situation but says time and wisdom changed his ways.

The singer was once a platinum-selling powerhouse on Diddy's Bad Boy Records in the early 2000s, when you gotta imagine he had plenty of options in the female department. But, now he's testifying to being a one-woman man, and seems to believe Ne-Yo will eventually narrow down his options too.