A friend of mine got the "stay away from my man" phone call the other day, reminding me of all the stupid "stay away from my man" calls I have gotten in the past. I'm a supervisor. I USE to give my subordinates my number but now I don't. They can call the office and the office will call me. Sucks for them but maybe they should be better men and make sure their women aren't so insecure in the relationship they feel they have to call any women on his contacts and harass them.
On the other hand, please don't be that woman either. If you suspect your man of cheating talk to him RATIONALLY no blame game, no arguments. Find the root concern. Try to trust each other. Discuss the end game. Do you want a future together or are you hanging on due to social pressures? Of he isn't happy in the sack he needs to tell you either how to improve or leave. You need to accept this and compromise or start figuring out the next step into a single future.
Because that woman who calls other women to vent her own insecurities just violated her man's trust by going through his phone, she likely didn't bother to gather evidence past "my man recently called this person" so she concocted the worst impression of her man and this random woman without meeting her and she should know her man better than that. So what man would want to be with a girl crazy, spiteful, confrontational, invasive, and insecure enough to do this? And what self respecting woman would fight over a man who doesn't make her feel secure in their relationship? Don't be that woman.