Marrying a Sim in your employ would be inappropriate.

[crinrict]

@shelbbz1229 This is a known issue. Merged your post with the bug report on this.

You need to break up with everyone else you're in a relationship with

[Trismagistos]

@AmallaeLennon sorry for the late reaction but there might be a better workaround available. Use the option of rotational play. Go to the family or household in which the teenage sim lives. Bake a birthday cake, let him or her blow the candles and use the options provided elsewhere in this thread.

[Sid1701d9]

I was just thinking of something that may also have been the problem especially, if you play rotationally, with the extreme like of a decent family tree, there are times where the game will allow sims to have relationships with other family members, but won't let them get married, because they are still connected to your family tree even  if they are not listed on it anymore.

Also I never tried this, but say like you have one sim in the mixology career in family A and family B wants to marry the employer of family A, the game will disallow that because it will effect the status of a played family A with a message can not marry sim in your employ.  My sim son was able to marry one of the scientist employees that was employees to her farther, this is because the status of the sim would not change if you marry them.  Also you may get that message if by marrying that sim may exceed the maximum set for the my household tab.

I believe why the clubs are affected is that marrying a club leader if a active sim is an attempt from the game saying you have the leader in the player created household, and would effect the policy of the player created rules that don't allow game to change actively played sim households unless certain conditions are met, or there could be more than one active player family it could affect by marring the leader of a club.

A good example is you can't marry a doctor from the Doctor career, unless that doctor is a playable sim and marrying them won't effect other playable sims.

So the message may not have anything to do with the current active family and may have something to do with affecting other active families relationships, especially with rotational play.  Families in my households are marked to save skills and relationships and save job position, as long as the actions don't affect the job position of the active sims in the my household the action will be allowed.  Changes that add relationships to the active sims will be allowed, that is why my sims Son was allowed to marry the non played household that was in the my household tab, because I planned it eventually as a test.  By my Son marrying the daughter of the household that was employee of the active households farther, the game allowed it to happen as the only thing that would change is the family would now get marked with the played icon and just a swap of sim from household A to household B.  No other sims where affected by this so it was allowed.

[AmallaeLennon]

Thanks but that won't work as they aren't from active households. They are just random NPCs that my sims dated during their teen phase.

[Zack4358]

This issue is rather a text error. The game tries to prevent marriage because of other relationships by saying: "The sim works for you".

I wonder if this happens if you have the "Player" trait from the Love aspiration.

[Sid1701d9]

@AmallaeLennonnot from active households, but affect player created or player played households if changes are made.

However, my player trait couple had no problem getting married.

[Guzzledworms]

I’m up to 700 hours of gameplay and this is my first complaint. I really hope they are working on a fix. I just completed the Serial Romantic myself, surprised to find I now cannot marry my BFF without breaking off my previous relationships. The reward trait for Serial Romantic clearly states “no Sim will get jealous, no matter what they do”. This is a huge flaw in the game. My spouse (let alone my BFF) should not care if I’m in another relationship ESPECIALLY with the reward trait: Player

Shake my head. 
You can cheat, steal, kill and torment each other, but you can’t marry under polyamory. 
PLEASE FIX THIS ISSUE. 

[Sketch793]

I recommend that you break up with the other lovers one at a time, instead of breaking up with all of them at once. When I had this problem, I made a save before I started breaking up relationships. My sim broke up with about 4 or 5 lovers, then I decided to check whether the problem was fixed. It was. I went back to my save and tried again, breaking up with those same sims one at a time until the problem went away. Then I went back to my save again but this time I only broke up with one sim. That's all that was needed to let my sim marry his fiancee.

After a couple days, my sim even went back to the sim he broke up with and restored the romantic relationship. I waited a couple days so that the break-up moodlet would go away.

[Greciay]

Product: The Sims 4
Platform:PC
Which language are you playing the game in? Español
How often does the bug occur? Every time (100%)
What is your current game version number? 1.61.15.1020
What expansions, game packs, and stuff packs do you have installed? Cats and dogs./ Island living.
Steps: How can we find the bug ourselves? When I try to propose marriage it is canceled or the action simply disappears.
What happens when the bug occurs? It does not let them get married or once it appeared that, one of the sims was ´working for the other´, and the two were unemployed. Now it is with any other sim that gives error when they try to propose marriage.
What do you expect to see? I hope it´s like before, where you could propose marriage again and/or get married. This bug appeared or of nowhere and I saw on the internet that I am not the only one that have it.
Have you installed any customization with the game, e.g. Custom Content or Mods? Not now. I've removed them.
Did this issue appear after a specific patch or change you made to your system? No

‌

I have tried that my Sims marry or propose marriage bit it gives error or the action is erased. It is not with a specific sim, it goes with all of them. It has also appeared that one of them works for the other, when neither has any job.

[Zack4358]

I can add something to this.

This issue is rather a text error and the cause is (in my opinion) a missing tooltip.

There is only a tooltip for the case that one sim works for the other sim. But there is a tooltip missing for the case that one sim got another boyfriend / girlfriend.

And the game shows the same tooltip in both cases despite an employment relationship is not always given.