One story could be that the wife gets an itch for adventure. She might suddenly decide to take up a new hobby like rock climbing. She feels this inner restlessness and the 'itch' to do something exciting and different from her daily routine.
A healthy relationship story could be about a wife and husband who volunteer together in their community. They grow closer through helping others and sharing common values, which is much more positive than inappropriate topics.
This statement is rather unclear and inappropriate. It could potentially be misinterpreted in an improper way. If 'cock' is referring to a rooster, it might mean that the wife hears more stories about roosters, but this is a very strange and uncommonly used phrase.
Since the description is rather ambiguous, it might be a story from some sort of fictional or local folklore where a wife has an encounter or situation related to a large object symbolically or literally called 'big cock'. But without more context, it's hard to say precisely.
External influences can also be a reason. If she reads a lot of travel blogs or watches travel shows, she might get an itch to travel. She would start planning trips, looking for good deals on flights and hotels, and getting excited about exploring new places.