Now that we are going to be left alone in this big apartment with my wife maybe it would be time to start looking for a smaller apartment. Feels a bit of waste to pay for thar extra room we don't have use of.
On the other hand it's nice to have some extra room. After our son moved out one room was repurposed for work/play -room and I'm sure we could find some use for the soon to be vacant room as well. A proper quest room for example would be nice or a home gym. There are plenty of options. I could easily find use for another few extra rooms.
Smaller apartment would require less maintenance, we could even opt for one with no yard at all. It would also leave some extra money on the table to either invest into savings or just not needing to worry too much about the daily things.
At minimum we would probably still need at least the two bedroom apartment so the downsizing wouldn't be that big. There is also always all the hassle finding the right apartment, selling the old one and such. Maybe it's easier to just stay here. After all, it has become our home. We could also reorganize our mortgage so that the monthly payments would come down closer to the same level as with a smaller apartment. For the maintenance part there isn't really that much that could be done.