I'm in Pakistan rn. Can't speak to Saudi Arabia but here a head scarf is pretty much compulsory for my partner. The cities are always more liberal than rural areas (where you see more burkha/niqab and way more scowling old men). From what I know Saudi Arabia is more conservative than Pakistan. Woman basically don't travel alone here and usually always have a male chaperone unless they are rich and part of the ruling class (rules don't apply to the elites here). People seem generally tolerant to foreigners who aren't Muslim.
Idk how your partner will feel but my partner has felt a baseline level of discomfort for her entire time here. Women spend alot more time inside so public areas are like 90% men and so we get a lot of stares. My partner would never travel alone in this country under any circumstance. Not sure how similar Saudi Arabia is but I think it's a bit more conservative/traditional.
Here alot of the public and commercial spaces are separated between male spaces and "family spaces". Ie if I we go a restaurant together we need to eat in a seperate room or behind a curtain because she is a woman.