My sims can't get married

So I want my sims to get married but the game doesn't let me. I planned a whole wedding and the moment was there but when I clicked on the wedding arch it says something like: Your sim can't marry her boss, she needs to quit her job first. But the thing is that they don't even have the same career! I tried multiple times, I tried to elope too and that doesn't work either. I made 1 of my sims quit his job and still the same message. I don't want my other sim to quit her job because she's level 9 and I don't want to lose that. Does anyone have an idea why this is happening?