Count how many conversations users have logged with other employees

We have an app that users in our offices are asked to log when they have conversations with their co-workers about monthly subjects. What we are seeing is that various users in a single office are accidentally recording that they are having a conversation with a co-worker that another user has already recorded having. We only want to log 1 conversation with each co-worker per month. I already have a field that populates "yes" or "no" whether the current conversation took place during the current month time period, and have a connected table that contains a list of every co-worker creating a "related co-worker" field. So I would like to have the form count how many times already during the current month time-period has there already been a conversation with the selected related-co-worker.


If we already have records like
Current Month?    Related Co-Worker
Yes                       Bob Smith
Yes                       Jack Jones
Yes                      Greg Doe
No                        Bob Smith
No                        Sam Garcia

If I were to add a new record for Bob Smith this month, I would want the form to indicate that there has already been a conversation with Bob Smith with this month, giving a conversation count of 1. In addition, if I add a new record for Sam Garcia I would expect the form to know that Sam Garcia does not have a logged conversation for current month and show 0. Any and all help is greatly appreciated.