Seems Marriott has updated enforcement policy on name changes on bookings and account sharing, in the cause of fraud prevention. Though it seems it has repercussions for spouses trying to check in under their partners reservation as well.

https://www.reddit.com/r/marriott/co...ges/?rdt=40344

https://viewfromthewing.com/internal...ockout-or-ban/

The TLDR is don't share your account with your spouse or anyone else, if you want to gift an award call up and do it.