Curious Skype contact

Please excuse my ignorance, I'm not at all computer or social media savvy so wanted to ask a question that I'm sure I know the answer to. Recently my partner opened up his Skype app and the name of a woman he used to date came up. There were no other names or contacts, just hers. He acted shocked to see her name claiming he'd never been active on Skype and denied of course having communicated with the woman who's name appeared. Would this women's name pooping up mean they'd had previous contact, or that he invited her or she invited him? Her phone number was no longer in his phone contacts so he acted awed like it was a web miracle that he could not explain. Internet searches havent answered my question. Could you? Please?