Photo: countrymusicislove.com

BRANTLEY GILBERT and JANA KRAMER'S relationship has progressed from "just friends" . . . to "officially a couple" . . . to COHABITATION!  Jana tells CMT Radio Live, quote, "I actually bought the house, and he is living with me, yes."

Jana's benefits aren't totally free, though.  She adds, quote, "He's paying his little monthly rent."

She says, quote, "It's hilarious.  You walk in and to the right are all my colors and sparkly clothes and then Brantley has the left side of the closet and it's all black. Actually, I take that back.  I bought him four red shirts, and they stick out like a sore thumb."

And if you're wondering how committed Jana is, well, sounds like she's all in.  Quote, "I am really happy.  [Brantley] is so wonderful, I cannot stop smiling around him.  He surprises me with gifts 'just because.'"