Kyle Richards, Mauricio Umansky Step Out Together for Daughter's Birthday

Here's a rare sight these days ... Kyle Richards and Mauricio Umansky hitting the town together -- but it's not a sign they've smoothed out their marital issues, it's just that they're great parents.

The separated couple publicly reunited in Bel Air to celebrate their daughter Portia's 16th birthday. The fam left a restaurant together Thursday night -- Mauricio was carrying what seemed like a gift or cake box ... and they even drove home together.

Kyle was behind the wheel of their SUV, and Mauricio rode in the passenger seat. It's the first time we've seen them out together in a long time ... amid what's been a very public separation, which they announced last summer.

Since the new season of "The Real Housewives of Beverly Hills" started airing, we've seen Kyle draw a line in the sand ... hinting on the show that their 27-year marriage might be coming to an end.

In one scene, she told Dorit Kemsley, "If there's no effort, we're not going to end up together."

While Mauricio and Kyle are still living under the same roof, Kyle's been hanging with Morgan Wade, who she insists is just a friend -- and we've seen Mauricio partying hard in Aspen with other women.

The couple went public with their separation in July 2023, but since then they've been on vacay a couple of times together as a family -- including a holiday trip to Aspen ... shortly after Mauricio's wild night out there.