Why isn’t Tony using his suits?
Reason is that he had an accident while out flying he got struck by a lightning (blame Thor for it) and it didn’t power his armor, instead it drained it and he fell from the sky down to the ocean under him. The suit was damaged and started to leak water and started to fill while it sank. He soon passed out and a week later he woke up at the hospital. Shaken by what had happend he got a bit freaked out and refused to use it for a long time. The broken suit now lays in a box in a corner in his workroom covered by a sheet.
Has this changed Tonys personality?
Both yes and no. Seek and you shall find answers.