Dreams involving attraction to someone other than your partner can often reflect underlying feelings or desires that you may be experiencing in your waking life. In your dream, the setting of a holiday suggests a time of relaxation and escape, which could symbolize a desire for freedom or adventure.
The brunette you felt attracted to might represent qualities you find appealing or exciting, possibly reflecting aspects of yourself you wish to explore or express. The guilt you felt indicates a conflict between your desires and your commitments. This could suggest that you are grappling with feelings about your current relationship or questioning aspects of your romantic life.
Consider what this dream might be revealing about your current feelings in your relationship and whether there are areas where you desire more excitement or fulfillment. It might be beneficial to communicate openly with your girlfriend about any feelings of boredom or dissatisfaction you might be experiencing, ensuring that both of you are on the same page.