The hotels in Mexico are pretty firm on the "honeymoon" requests. They'll say something like "unfortunately the hotel does not offer any honeymoon/anniversary/birthday amenities or any complimentary upgrades." That's very typical.

As for the confusion on the number of adults on the reservation, I'm guessing that this has to do with the fact that this is an all-inclusive resort. Maybe they are thinking that you have a 2-guest reservation and then you "added" an additional guest. As others have suggested, just show up. There's a review out there on another site regarding a similar issue, but the person had booked for only 1 and didn't include his spouse. Ooops. Additionally, Diamond member don't seem to have this problem.