Exchange Vows Grayed Out on wedding arch/No partner around

It is definitely back, the problem just began again for me. How is this not fixed...

Thank you! It has never happened to me before. I will try this during the following marriage. But this behavior is really strange. I had two weddings, one after another and I had the same problem with both of them. So I suspect it is actually a bug.

When I try to plan a wedding (both with My wedding stories and a basegame one), the game says that my fiancee isn't at the lot (they're both standing in front of the arch). pls fix this (and the rest of the game). The only way it works is through a "on-the-spot" marriage in the relationship tab.

Hopefully it works for you. I know I was surprised that something so simple helped me.  

Unfortunately nothing helps. I have tried changing the lot type (changed it to park: all it does it activates `Exchange vows', but at the end of the wedding they are still engaged. I will try to find a way or maybe somebody will give me an idea. In the meantime, all my sims will remain engaged. No more weddings, only babies.  Thank you for giving me an idea. 

I had the exact same issue trying to get my sims to get married with a wedding-type event. They would exchange vows but at the end reset and they wouldn’t be married. I had to wait until the MWS wedding event was over and then have them click on the arch to get married.

I encountered the same problem, what helped was trying to get married using the arch after the wedding party, apparently the event itself breaks the marriage.

I found this bug Exchange Vows Not Working | EA Forums - 12297968
We can vote there

j'ai le meme probleme avec l'arche de mariage : impossible d'echanger ses voeux et donc de se marirer

I had that problem yesterday, well, kinda. There was an option to exchange vows and kiss, which they did, but the activity wasn't ticked off in the list of wedding activities, and when I checked their status after the wedding, I found out they were still engaged. So I clicked on the arc, saw the option "marry Sim" and clicked it. They did get married then, thanks to that, but by that time, all the guests had already left.

Weddings really are such a  hit and miss. The last one I did was SO annoying. Guests showed up late, including the bride's mother who was also supposed to officiate the wedding. We're talking hours here. The bride's mother arrived when the ceremony was all but over, and at least the guests remained mostly seated throughout the ceremony. But it takes them forever to react to prompts or go to where they are supposed to go, e.g. the dance floor, or that champagne bucket. You have to time those activities carefully and give the guests time to react. Otherwise, if you, say, click on "throw rice" once the guests are outside, they might do just that, but not right on the spot. No. Last time, they followed the groom outside and straight into the building where the restrooms are because he needed to use one. They threw that rice while the groom was in the restroom 🙄

And don't get me started on the clothes. Most of the Sims at my last wedding were Sims I created for the various households I play rotationally, and in the past, wearing whatever I had picked for them never was an issue. This time? One of them showed up in a military uniform even though she's a chef, the bride's older brother wore a sweater with a scarf, and one of the bride's friends showed up in a white flowing gown that looked very much like a wedding dress. The bride ended up kicking her out for that.