PHYSICAL INFIDELITY happens when you sexually engage with another person; but there’s also EMOTIONAL INFIDELITY, which happens when you let your heart be led by feelings and fantasies about other people. You take from your partner what is exclusively theirs and give it to someone else.
This is why Jesus warned us that just by looking at someone with desire already consists of adultery. He knew that every physical adultery begins with emotional adultery, so He gave us this tip: “Don’t even think about it!”
Cheating is filled with adrenaline; but its results are sheer guilt and depression. It’s better for you to use your energy to start a relationship where you’ll never need to look for what you need outside of it.