AskEveryoneElse: SO on a dating website

Dear Everyone Else,

You've been seeing your SO exclusively for a yr. Your friends calls to tell you that they saw your SO on a dating website and that they logged in 10 days ago. SO admits they were on the site, but says that it was just to surf profiles because they're curious about what people write in them. SO shows you that there have been no communications with anyone for a yr, but they could have been deleted. How do you proceed?

[Your answer here]