General Meanings:

• Guiltiness –  Dreaming of cheating on girlfriend meaning in common sense is about feelings and emotions, that you might have in case of such activity.
• Unhappiness – Cheating on your girlfriend in dream also can mean that you have insufficient satisfaction from relationship with girlfriend.
• Changes – To dream that you cheat on your girlfriend can indicate changes that you wish in your life or in the relationship.

* Please, see meaning of an adultery. See dreaming of adultery meaning for complete understanding your dream about cheating on a partner.