why husband and wife always fight on little matters?

Fighting is normal in a relationship. 

BUT, Don't fight in public. This needs to be a hard and fast rule. Not only are you putting each other in an embarrassing situation, but it's very uncomfortable for the people who witness you fighting. Whether it's around strangers or friends, no one wants to see a couple fight.

You'll never be able to solve the issue in that environment anyway, and the awkwardness of it will only escalate the problem. If you can't leave right away then couch the conversation until you get home. One advantage to this is that it gives you a chance to cool down a bit by the time you readdress the problem.
 Don't fight in front of your kids. If you have children, they won't bear this and a negative for life time on the minds of children. If there's one guaranteed way to stop a fight dead in its tracks, it's that. We picked him up, hugged as a family, and explained sometimes mommy and daddy get upset but still love each other. That moment broke the tension enough to allow us to finish what we started in a calm manner while our son went back to playing in his room. Once we are finished, we went to our son, holding hands, and told him everything was fine. We told him to remember that sometimes people fight but when they love each other a lot; they always find a way to make things good again.

 Don't fight to hurt the other person. When you're angry, your ego tends to take over, and the ego is all about war; wars don't exist without trying to hurt another person. When you go for their sensitive trigger points, their vulnerable place, you've hit below the belt and that is unfair and immoral. It's critical to remember, above all else, even in the heat of the moment, this is supposed to be the person you cherish the most in your life and who has put his emotional trust in your hands. Words do hurt and they are not easily forgotten.

 Don't bring things up from the past.

In those heated moments, it's easy to want to bring the past things that weren't completely solved just to show yourself with more suffering. That's a big no. All that does is take your attention away from the matter at hand and will extend, unnecessarily, an argument that might have been able to be solved rather quickly. Even if the present fight is related to a past situation.

THE MAIN REASON OF ARGUMENTS BETWEEN WIFE AND HUSBAND ARE

• THE DIFFERENCE OF TASTE/INTEREST, MEANS TO SEE LIFE IN THEIR OWN ANGLE, IT'S NATURAL. IN THIS WORLD NO TWO PERSON HAVE SAME THOUGHTS AND IN OPPOSITE GENDER IT IS VERY DIFFICULT, IT IS IMPOSSIBLE TO FIND TWO OPPOSITE GENDER HAVING SAME THINKING SO ITS NATURAL THEIR WILL BE ARGUMENTS ON LITTLE MATTERS.
• THE WIFE ALWAYS REMEMBER WHAT HAPPEN IN THE PAST AND LIVE ACCORDINGLY AND HUSBAND ALWAYS THINK ABOUT FUTURE. THE WIFE MANY TIMES GIVES YOU REMINDER AGAIN AND AGAIN ABOUT LAST TIME SHOPPING AND PICNIC. HUSBAND ALWAYS THINK ABOUT MONEY MANAGEMENT AND HOW MUCH LEFT AND HOW MUCH REQUIRED TO COMPLETE THE MONTH. HE ALWAYS IGNORE WIFE ABOUT OUTING. WIFE ALWAYS SAID THAT YOU GIVE ME NOTHING, I DON'T HAVE ANYTHING TO WEAR I NEVER ASK YOU ABOUT SUIT SAREE. BUT YOU DIDN'T HEAR. HUSBAND SURPRISED LAST WEEK SHE PUCHASED 02 SUITS AND 01 SAREE AND OTHER ITEMS. HOW HE MANAGE, SO WITH PASSAGE O TIME HE UNDERSTOOD AND HANDLE WELL.
• SO UNDERSTANDING WITH WIFE IS VERY IMPORTANT, IT CAN'T BE UNDERSTOOD WITHOUT DEEP THINKING AND OVERALL CIRCUMSTANCES. IF YOU UNDERSTOOD, THEN YOUR LIFE RUNS VERY SMOOTHLY AND IF NOT, THEN LIFE BECOME HELL.
• IT IS UPTO INDIVIDUAL ITSELF HOW TO UNDERSTAND HOW TO MANAGE IT. OTHER PERSON CAN'T DO ANYTHING, ITS YOU AND ONLY YOU WHO HAVE TO MANAGE ALL THESE THINGS.