Evidence of online dating: If your spouse has signed up with an online dating sites like match.com, ashleymadison.com etc. then you can use it as evidence in the court to prove the intention and opportunity for the infidelity of your spouse. Ask family and friends: In most cases of infidelity, family and friends of the culprit may have some information in this regard. So you can ask family and friends to know in this regard so that you can resent them in the court as evidence.