Yolanda Foster isn't the easiest person to get to know -- at least according to her Real Housewives of Beverly Hills co-star, Kyle Richards.

During a new interview, Richards shed light on why she and Foster have never been very close and discussed her sister Kim's possible full-time return to the show.

"She’s been very hard to get close to," Richards told Us Weekly on Tuesday during an event to promote SculpSure, a laser fat-reduction treatment. "I tried and made an effort, and I felt like it was never reciprocated. It’s very hard to get close to her."

While Richards may have struck out on a friendship with Foster, that certainly isn't to say she doesn't like her. In fact, Richards finds Foster to be a "nice person." As for Foster's friend, Brandi Glanville, Richards feels a bit differently.

After getting into a bit of a Twitter feud about a misspelling last week after Glanville's pre-taped segment aired during the season six reunion, Richards ended up blocked by her former co-star.

"She spelled it L-A-D-Y-S, and she tagged Andy [Cohen]!" Richards explained. "And I tweeted back, 'LADIES.' And she has me blocked on Twitter! So we can’t see each other."

As for her sister's possible return to The Real Housewives of Beverly Hills season seven, which is expected to air sometime later this year, Kyle said she was on board with a return.

In addition, Kyle said Kim Richards is "happy and doing well and strong."

"I honestly think the show is even better with her on it," Richards explained. "My daughters, she’s their favorite Housewife! She says the funniest stuff."

Richards' comments regarding Kim come just weeks after a Life & Style source claimed she was threatening to quit The Real Housewives of Beverly Hills if her sister was brought back.

“Kyle put her foot down,” the insider claimed. “She’s concerned the fame and publicity will derail Kim all over again. [Kim] has finally managed to get sober and take control of her life, but she’s still very vulnerable."