When couple's gently bite each other's lips without drawing blood it is a sign of a 'feisty' relationship.
情侣轻轻地用不会导致流血的力度咬对方的嘴唇，代表着一段“充满活力的”感情。
Phil explained that nibbling your partner shows a strong physical passion and may be an indicator that two people have a 'healthy, and perhaps athletic, sex life'.
菲尔解释说咬对方的嘴唇意味着强烈的肉体激情，可能暗示着双方拥有“健康甚至活跃的性生活”。