Fighting in a relationship is inevitable and highly usual. You may not fight at all during the initial period of your relationship but somewhere along the road in future, it is bound to happen. So, is it good to have a fight or bad for your relationship? I would say it is good. Fighting helps you grow and learn a lot about your relationship. It increases your love and you have a stronger bond with each other after a fight.
If a couple says that they never fight than that should actually make them worry. Studies show that no fight in a relationship leads to a boring and less active type of relationship. During an argument, you get to discuss all the things that you might have kept bottled up, which again is bad. Not talking about the things that bother you about your partner is like setting a time bomb inside us, that only gets worse with each passing day. When you discuss all the things with each other that bothers you both, you get to know where you go wrong and improve yourself. More importantly, you feel better and lighter once you keep no secrets within you.
Since you have expressed all your thoughts and emotions during your argument, your partner can show understanding and act accordingly. When you make up after a fight, it feels better than before. Your intimacy and sexual life improve too. It is not always others, sometimes we can be at fault too. During a healthy fight, you get a chance to accept that you made a mistake and you can apologise. It makes you more understanding and mature. A fight demonstrates that you are both humans and it is obvious to have separate opinions about the same things.
It is safe to fight as long as it is a healthy one. The one that is free from saying hurtful things and use abusive language. Do not forget that you love each other and an ugly fight can make it impossible to feel the same way you once did about your partner.