I feel the same way...I honestly cannot wrap my head around it in the least...String Theory would probably be more comprehensible to me (Social Science major here).

Recently I found out an ex of mine who I had always believed to have cheated on me, actually did several times and would go around gloating about it and would even sleep unprotected with other people then come back and initiate things with me. He had been telling this stories to his ex fiance and talking about how hilarious he thought it was. I still can't even begin to wrap my head around how cheating on someone is easier/better than ending the relationship or at least being honest and talking about it after the fact.