Because less crowded and more relaxed than being at a local park. DH is very conservative about covid so this felt like a huge win. Then we get there and df (who traveled by plane a couple of weeks ago) isn’t wearing a mask (the rest of the family is). Her house so she can do whatever she wants but it was upsetting and I felt bad given that it took a lot for DH to get comfortable about being at someone’s home. And we were sitting at an outdoor table so not 6 feet apart. We didn’t eat but dc had snacks so obviously no mask. I suppose I could have left but dc really missed these friends. Just feeling bad and hope it was ok.

I think one unmasked person outdoors is not a big deal. It would ping you for contact tracing but small outdoor gatherings haven't been implicated for transmission.
These are things to talk about before going over. We went to see friends yesterday and before we came df asked me if we were ok with everyone being outside and adults being distanced in the backyard and everyone wearing masks when inside and we said of course.