We had the same problem in 2 small areas of our wallpaper on the back of a dinette bench and the wall above(both in the slide out). What I did was cut the wallpaper straight down with an exacta knife peeled the loose wall paper back, reapplied some good quality Weldbond glue and replaced the folded wall paper back over the reglued area. It has held perfectly and you have to look very hard to see where the repair was done. The cut back and reglued area almost looks like the natural grain in the wallpaper. I did small areas at a time to accomplish this. The repair has stayed for over 2 years now.
You may want to try a small area on one of your less visible walls to see if this might work for you.
Good Luck.