Dreams about infidelity can be quite common and often reflect inner conflicts, emotions, or fears regarding relationships. Here are some interpretations of the different elements in your dream:

1. Cheating on your girlfriend: This aspect might symbolize feelings of guilt, temptation, or dissatisfaction in your current relationship. It could also indicate that you are exploring unresolved feelings for your ex or questioning your current relationship's dynamics.
2. Family walking in: This could represent your fear of judgment or the consequences of your actions. It might also suggest that you are concerned about how your relationships affect those around you, particularly your family.
3. Your girlfriend's hurt reaction: This might mirror your anxieties about hurting those you care about or the consequences of your choices. It could also reflect a fear of losing trust or connection in your current relationship.
4. Ex-girlfriend running away: This could symbolize feelings of guilt or regret about past choices. It may also indicate that you recognize the past is behind you and that you want to move forward.
5. Sister's forgiveness: This might signify a longing for understanding and support from your loved ones. It could also highlight the importance of familial relationships and the idea of making amends.

Insights and Advice:

• Reflect on your current relationship: Are there areas where you feel unfulfilled or conflicted? Open communication with your partner may help address any underlying issues.
• Consider your feelings about your ex: Are there unresolved emotions or lessons from that relationship that you need to confront?
• Think about the role of family in your life: Are you seeking their approval or support in your relationships? This may be an opportunity to strengthen those bonds.

Overall, this dream may be prompting you to evaluate your feelings and relationships, encouraging you to seek clarity and honesty in your connections.