God's blessings come with certain burdens. Not that the blessings are flawed; it's us... we're flawed.
I'm reminded of II Corinthians 4:7, "We have this treasure in earthen vessels." While our ineptitudes allow the glory of God to shine more brightly (in contrast to our lack of glory), our ineptitudes also get in the way of our attempts to be godly ourselves (obviously)! Our feet are made of clay. We are, after all, just dust.
So, God blessed Abraham and Lot with great wealth ... so much so that the land that they lived on couldn't sustain both of their families at once.
Now, who gave them their riches? God did! But, their wealth became a cause for parting. That solution seemed like a good one. Abraham meekly gave Lot the first choice of the land that lay around them.
Lot should have been like Ruth with Naomi (Ruth 1:16), or like Elisha with Elijah (II Kings 2:6). He should have insisted on sticking with his godly companion. But, Lot's propensity to follow after the lust of the eyes (I John 2:16) immediately showed itself... he chose the cities that lay in the well-watered plains near Sodom. That choice would eventually prove to be a fatal one for him. Abraham went the other direction and continued his rural nomadic life in the land that God promised to give him.
At the beginning of this chapter Abraham and Lot came out of Egypt (representing the world) and found themselves living at Bethel (which means, "the house of God"). The chapter ends with two statements that give us a distinct impression of the opposite directions that these two men were taking. Verses 12 and 13 say that "Lot... pitched his tent toward Sodom. But the men of Sodom were wicked and sinners before the LORD exceedingly." Sounds like he was headed in the wrong direction, eh? Verse 18 says that "Abram removed his tent, and came... and built... an altar unto the LORD."
Perhaps the schism was simply indicative of the hearts of these men. Their conflicting priorities made their disconnection ultimately inevitable either way (Amos 3:3).