Former New England tight end Pharaoh Brown says Patriots players had no idea about Bill Belichick's 23-year-old girlfriend last season ... telling TMZ Sports the coach never once brought her up.

Brown says Belichick was all ball during the pass catcher's one season in Foxborough this past year ... keeping things solely about football -- and not on how his love life with Jordon Hudson was going.

"One thing about Bill Belichick," Brown told us out in L.A. this week, "He's one of the greatest coaches 'cause he keeps it professional. He knows how to keep the main thing, the main thing, right?"

Belichick and Hudson first met on a plane ride back in 2021 -- and after Belichick's split with Linda Holliday in 2022, the two began to date. Currently, they're still going strong -- with Hudson having moved in to the 72-year-old's Hingham, Mass. residence around the start of the new year.

According to Brown, though, despite the couple's apparent love ... Pats players were kept in the dark about it all.

But Brown told us he wouldn't have had any problems with it if it was brought up during the season ... telling us, "Everybody lives their life how they want to live their life. There's no hard feelings."

In fact, Brown -- who just signed with the Seattle Seahawks this offseason -- wished the pair nothing but good things going forward.

"My whole thing in life is like everybody find love and be happy," he said. "If he's in love and he's happy, that's all you can want for another man."