Well, nothing against your husband, but the first thing he should have done was to remove the tile. What method did he use to lay them down, are they glued? If so then my guess is that the tile was not properly cleaned and roughed up enough so that the glue can get a good bond.
Do you know what type of adhesive he used Gloria? Should have used a good urethane product like Bostik's Best. Also, did he install solid or engineered wood? Solid wood should never be glued down. It moves too much and needs to be nailed. I agree that it is always best to remove the tile first, but since that is water under the bridge, all you can do at this point is to inject some more adhesive under the wood using an injection kit. Put some weight on it after that for a few days and you should be fine.
NEVER install hardwood over ceramic tile. At this point you can try a DRI-TAC Injection kit to inject moore glue into the areas that are popping but in the long run it would be best to pull it up, remove the tile and start over.
Well, nothing against your husband, but the first thing he should have done was to remove the tile. What method did he use to lay them down, are they glued? If so then my guess is that the tile was not properly cleaned and roughed up enough so that the glue can get a good bond.