While this question is for everyone,it depends on how you and your wife understand each other in the house and how frequent your wife move from outside and coming back to your house,if your wife goes to market all the time bear it in mined that she might cheat on you,women are not trusted at all so you need to do DNA test ,it help in a marriage relationship,I support DNA test
This is were you are misunderstanding this, you can't accuse someone because of a regular market, if you have a family that doesn't buy things in buck but only what you can use for the day, your wife will definitely go to the Market on every blessed day because there is nothing left to eat in the house since the last market has been exhausted, so actually your food stuff purchases depend on how consistent or rarely she would be on the market, if you have done your part in making sure there is a limitation in going to the market then you can suspect if the market activities is becoming unbearable.