Brandi and Jonathan — whom she calls "J.R." in the episode — actually met through Kyle Richards' husband Mauricio, since Jonathan is a real estate agent who works for Mauricio's company, The Agency.
In fact, Jonathan is the guy whom Brandi was eyeing at Kyle's White Party in 2012, and he is the dude whom she is rumored to have had sex with in the bathroom at the party, although Brandi denies it.
Then, starting in spring of 2012, Brandi started seeing Jonathan, although it was casual for much of the time. They broke things off at the end of the year, with Brandi tweeting in December 2012, "I’m sooooo over men right now! I’ve just decided I’m gonna be single for a while! Yeah me :)"
However, that apparently didn't last too long. Brandi and Jonathan got back together at some point in 2013 and were off and on for much of the year.
Indeed, by summer of 2013, they seemed to be very tight, with Brandi tweeting about him in August, "If you're looking for a place in L.A., call Jonathan Ruiz @TheAgency32 he is my personal real estate agent, very handsome & a sharp dresser :)"
She also tweeted in August, "I'm missing a very tall handsome Latin man this a.m.... #feelingneedy," which is clearly a reference to Jonathan.
However, by September, the two appeared to finally be over for good. "Ex-boyfriends are ex for a reason! #dontgoback," she tweeted on September 3, 2013. Yikes.
So it appears that these two are finally dunzo. Then again, with their history, they very well could have gotten back together in the time it took you to read this story.