Is your partner cheating on you? Pay attention to these potential signs of infidelity . 18 Jun LIP-LOCK LOYALTY: Can kissing be like a flirty handshake as opposed to a gateway to sex, cheating or heartbreak? Is kissing cheating?. Distrust and accusations of cheating may occur when your partner has a cold sore If all you have is the visual of a blister on your partner's lip, the verdict is.