All public establishments in the Kingdom have to have methods to keep women and men as apart as possible, whether it's different hours for families and for men only, or physical barriers separating families from singles, or even not allowing women into places at all, forcing them to order from a walk-through window, in the case of many restaurants here. In restaurants with separated family and singles sections, there will be a barrier of sorts around each table, allowing women who wear the facial veil, the niqab, to remove it and to eat in peace without strangers seeing their faces.
Luckily, very few places that I am likely to go will check to see if I'm actually related by blood or by marriage to my dining partners. I met a friend for dinner a few weeks ago in Riyadh. We accidentally got there 10 minutes early, during prayer time, so we had to wait outside until the doors reopened. (All businesses in Saudi Arabia must close by law during prayer times, five times a day. Normally prayers last about five to ten minutes... closing time is usually closer to thirty minutes here. We can discuss Saudi inefficiency another day.) We were finally escorted upstairs to our booth, and once the waiter handed us our menus he closed the curtain behind us, leaving our "family" to dine in peace. Every time the waiter had something to deliver, he knocked first to give me time to reveil if I wanted to do so. It was a surreal experience.
Riyadh has some good restaurants, especially ones that cater to the large migrant populations here - Indian, Filipino, Sri Lankan, etc. It's one of the few avenues we have to get out and socialize with friends outside the DQ. I'd like to visit a few more restaurants here, which I will do as soon as lockdown's over - seriously, this is starting to get on my nerves.