It's your partner's safety and sense of safety, so first off, they should what you need to to feel secure. Yes, Bellevue is generally very safe, but crime can still happen, and it's everyone's right to take whatever precautions they feel they need to. Pepper spray is nice to have as a deterrent if you need it. It's just a little piece of mind and can help you get away from someone if absolutely needed. I believe the gel kind is recommended as there's less likelihood of spray blowing back at you, and Bellevue does get windy. My other general guidelines as a downtown resident who walks everywhere are - stick to well-lit, busy arterials whenever possible where there is more traffic, even at that hour. Don't cut through alleys, parks or darker side streets. Avoid the transit center, it can get kind of weird even in broad daylight. Use your spidey senses - pay attention to surroundings (not the phone), head on a swivel, if you see something that causes any ounce of concern, cross the street or change direction.

Not to cause concern, but I'm a tall dude that works out regularly, I can put on a very effective scary face and look intimidating if I need to, and I've occasionally been hassled on the street by people that seemed intoxicated on something or other. Nothing serious resulted, but these things can happen to anyone.

Is your spouse able to talk with work and share their concerns? You've outlined that rides are not always available at that hour, or that it's not really convenient for you to go with and then leave them outside if the building isn't open. Maybe adjusting the schedule to later hours, or maybe they can help partner with someone else that also walks, or drives, and make some kind of carpool arrangement.