How can I know my girlfriend had sex with someone else?

or:How can I know my girlfriend had sex with someone else?or:Physically you can't.....you need to catch them in the act - if you believe she is cheat

or:How can I know my girlfriend had sex with someone else?

or:Physically you can't.....you need to catch them in the act - if you believe she is cheating on you.

Tags:sex,