That is something lots of people are hard on themselves about. but the thing is.... your not in another relationship with your ex, your in anohter relationship with a new person. so you have new feelings. its different to your ex. every relationship is new and different with different qualities, dynamics, you love him for different reasons that your ex. so why would it be any easier?
if it was easier you would think that you didnt invest your whole heart into the relationship.
if you fall in love and break up its hard. no matter how many times it happens.
.....