The singer shared her honest opinion on the sitch in her new sit-down with Interview Magazine, sharing her theory about Kyle's current relationship status amid her separation from husband Mauricio Umansky ... something RiRi is attuned to.

When Rihanna is asked point blank if she believes Kyle and Morgan are an item, she says ... "I mean, duh. Listen, I love Kyle. It’s weird commenting on her relationship because I don’t know the facts."

She continues, "I just feel like she was able to re-observe her marriage through a new lens. For once, someone else made her feel valued, made her feel like she was cute and quirky and fun and all the great things that maybe were taken for granted before."

Finally, Rihanna ends by saying ... "And that’s why I believe that there’s something with Morgan, because sometimes, it takes that for you to fight for what you deserve."

Clearly, she feels like Mauricio has done Kyle dirty ... and she's all for Kyle doing her thing.

Rihanna was asked about a flashback moment 'RHOBH' implemented recently to harken back to something that went down in Season 1 -- a psychic predicting things would fall apart for Kyle and Mauricio. Rihanna says she found it messed up that Bravo added that.

There's been a lot of speculation something was up with Kyle and Morgan for about a year now, as they've spent a lot of time together -- even though we've heard they're just pals and Kyle has a business relationship with Morgan. Of course, not many are buying it's just that.