Married Sims become boyfriend/girlfriend again after a few days

I am experiencing a bug in The Sims 4 where married Sims eventually lose their married relationship status.

My Sims get married normally, but after playing for a few in-game days, the game no longer recognizes them as married. When I check their relationship, they are listed as boyfriend/girlfriend again, as if they had never gotten married.

This happens without me performing any interaction to end the marriage or change their relationship status.

Steps to Reproduce:

Create or select two Sims.

Build their romantic relationship until they can get married.

Have the Sims get married normally.

Continue playing the household for several in-game days.

Check the relationship between the two Sims.

After a few days, their relationship changes from married back to boyfriend/girlfriend.

Expected Result:

Once two Sims get married, they should remain married unless the player performs an action that ends the marriage, such as divorce.

Actual Result:

After a few in-game days, the game changes their relationship status and they become boyfriend/girlfriend again, despite never getting divorced.

Additional Information:

The issue happens after the Sims get married, without any action from me to change their marital status.

I use MC Command Center (MCCC) and Relationship & Pregnancy Overhaul (RPO).

The issue happens in all of my saves.

The issue only seems to affect Sims that I currently control or have controlled at some point.

This happens repeatedly and negatively affects the progression of my Sims' families and stories.

I would appreciate it if this issue could be investigated, especially since it occurs across multiple saves and consistently affects Sims that have been under my control.