Relationships

The thing I can't seem to understand about relationships is why we have to hurt one another. I mean it just seems like you should be able to have a relationship with a member of the opposite sex and not spend most of your time making one another feel bad. I don't know of a single relationship where the guy and the girl don't end up doing one another more harm than good. They leave each other broken and scarred and then go on to repeat the process with someone else. I know it's not possible for it to be anything but good all throughout and then have a happy ending, but I do ever so wish that this were the case.