Is it infidelity:?

A number of years ago I was enjoying my Saturday morning coffee when the single mom that lived two houses over knocked on our door. My Dear Wife and her were good friends so I let the neighbour in and went about my morning chores. Eventually I went into the kitchen for another cup of coffee when I heard the neighbour tell my Dear Wife that she wanted to borrow her husband (me) Dear Wife asked me if I wouldn't mind helping the neighbour out and thinking the neighbour wanted help rearranging the furniture or something like it I agreed. Once at her house my spidey senses were tingling when I found her two kids were visiting Grandma for the day. Then the neighbour said she needed help in the bedroom. How was I to know that the two women had this all planned out days earlier?