Here a woman with a duplicate spouse:

Merging M63V-VWX into GM8Q-DVJ, I get this merge screen:

No marriage information is displayed. There is no indication of what is going to happen with the spouses as I proceed with the merge.

In the result:

Ignoring that there are more duplicates to take care of, the marriage information for Hans and Anne has been lost.

This is not good.

As I have observed this before, I have found that if I am careful to merge the Hans without a marriage date into the one with a marriage date, things are fine. I could accomplished this by switching the merge, but there is no indication during the merge that I should have switched.

If I had turned on Group by Family, even though there is no obvious reason why I would want to, I would have seen this:

But there is still no warning that if I continue I am going to lose the marriage information and there is no way to choose to keep the marriage information.

All I can do is switch the order, even though there is nothing here to suggest that would be a good idea:

Now what has happened to the marriage information? Oh, yeah, have to click that Group by Families slider again!

Now if I continue through the merge, the marriage information is kept:

Please improve the new merge to remove the risk of inadvertent loss of marriage information.