No one can promise they’ll never hurt you, because at one time or another they will. The real promise is if the time you spent together will be worth the pain in the end.
You don’t always have to be sweet and lovey dovey all the time. You can be the assholes to each other and be mean. That’s when you know there is comfortableness. Making fun of each other, calling mean names, abusing each other. Abusing as in joking around. The playful fighting. That’s another way to show love.