Astrologically I think I can speak to this some. I'm a pisces sun with aqua mercury. I love aqua suns. And my best friend is aqua sun pisces moon.So anyways, its often written that aqua's like there independance and they show affection by giving their partner space, some are afraid of getting close. However, I don't completely agree with this about aqua's. They are a fixed sign (i have a fixed moon too). I think our fixed moons, make it very hard to move on and get over things. We feel things very intensely, both love and heartbreak. Pisces are also known for 'swimming' away when things get too close, probably out of fear of getting hurt and also because they are a mutuable quality. They have a need to be active and experience many things. This does not stop them from loving who their with though. We are romantic and emotional, we do care. And an aqua moon as an air sign probably gives the ability to intellectualize ourselves into thinking it's okayto do things like cheat, until we realize later how we really feel.
Cancers in some ways have a lot in common with what I described. They scuttle from showing their true feelings, and are also afraid of getting hurt. A damaged cancer would probably drive their partner away, before he/she leaves. They're very self protective. Will he be able to understand why you did what you did? Maybe, maybe not. Cancer's feel intensely too and theyre moods and feelings change like the phases of the moon. His emotion and pain may prohibit him from understanding your motives.
All I know is that cheating usually happens for a reason. Something in your relationship is not satisfying you or you don't trust your partner to be faithful to you.
None of what I wrote may make you feel any better. But in my opinion these may be lessons in life that a young pisces/aqua person has to learn. And I do believe that once you recognize the behavior and understand it, you will learn from it.
It's not easy living with guilt but it will stop you from making the same mistakes in the future and find yourself in a more successful and fullfilling relationship.
The right person will come along, and what your feeling will seem like a distant memory that never happened. I truly believe that 