Why wont muslims stop hurting each other and unite together. (sunni n syiah n others)?

There are some things in the way. They're following their own traditions now and aren't willing to let them go, in general. Each group is proud of what it has and the identity they draw from it.

6:159. As for those who divide their religion and break up into sects, thou hast no part in them in the least: their affair is with Allah. He will in the end tell them the truth of all that they did.

30:32. Those who split up their Religion, and become (mere) Sects,- each party rejoicing in that which is with itself!

21:92, 93 - Verily, this brotherhood of yours is a single brotherhood, and I am your Lord and Cherisher: therefore serve Me (and no other).

But (later generations) cut off their affair (of unity), one from another: (yet) will they all return to Us.

It's a long, historical explanation, the bottom line is that the Middle East has been a hell hole for 8000 years. Muslim tribalism has continued since approx 600 AD. Tribalism is rife all over the planet, not just in the ME, but the close proximity of these two, and their beliefs that each of them and each of them alone is correct, leads to intolerance.

So, it has been this way for 1400 years. And it won't ever change, sorry....not until they dump religion, and decide to be a community of people, rather than waring tribes each convinced of their own righteousness

Because people of these and many other religions often save their most hateful and perverse acts to perform in the name of a supposed loving deity. As the late, great George Carlin put it, "My god has a bigger dick than your god."

I wish I had an answer.

Heck, I wish my fellow Christians got all along better.

their too ignorant