Browse in private dating site
Run a search on google for their email address, phone numbers, full name, and profile picture.
For example, you could download Flexi Spy on their phone (for a hefty price of 0-0, depending on the surveillance mode you choose), to track activity - although there are potential risks and issues that might arise depending on your jurisdiction and the potential for being caught in the act.
If nothing else works (or you don't have the time to conduct an exhaustive search that may or may not be conclusive), consider hiring a private invesitgator.
One of the biggest issues that she and her friends have with online dating isn’t so much the people they meet, but which site they meet them on.
For the computer, your best option is keylogging software, which will track all web activity, emails, and logins (even if your spouse clears the browser history).
Ultimately, if you’re worried that your significant other is on a dating site, there are many options for sleuthing (ranging from a quick scan through emails and browser history to more intensive—and expensive—actions).It’s why I’ve created this handy guide to the 11 best dating websites and apps available right now. • The 20 most useful dating websites This site describes itself as the way to meet ‘the most successful and attractive singles.’ It asks users to fill out their job title and education, and links to Facebook so you can view their social circle.