“Keep your friends close and your enemies closer.” Quotations are often worded in a broad enough way to apply to a variety of situations. They’re usually open to interpretation.
The “friend” in this situation could even be the husband. After all…isn’t a spouse like a friend? I would say so. So you keep your husband close to you. And you keep his friends close to you. His friends are not necessarily the wife’s enemies…BUT…she can get to learn more about HIM from his friends. After all…some friends may have been in your life before your spouse ever showed up.
And the “enemies” or “competitors” in this scenario…would be the flirtatious coworkers. You keep them “closer”…so that you’re more aware of what is going on. So that THEY can see, as Psquared suggested, that the wife is more than just a framed picture on his desk. So…that they can see…UP CLOSE…that she DOES INDEED exist in flesh and blood. And by going to future parties…you keep the enemies within eye and ear shot to see how their actions can affect you.