David as King, Snapshots from 2 Samuel

2 Samuel, Chapter 2

On the Situation After Saul Died and Before David Assumes Kingship: 

This was a decisive and important move for it immediately alienated him from the Philistines with whom he had taken refuge and made an alliance; it signified the quasi-independence of Judah from Israel, an attitude which would find complete expression at the division of the kingdom after Solomon’s death (1Ki_12:16); and it asserted David’s reign as being in rivalry with that of Saul’s son, Ish-Bosheth, who succeeded his father in the North. -BKC

On Hebron

Unto Hebron - The metropolis of the tribe of Judah, one of the richest regions in Judea. The mountains of Hebron were famed for fruits, herbage, and honey; and many parts were well adapted for vines, olives, and different kinds of grain, abounding in springs of excellent water, as the most accurate travelers have asserted. -Adam Clarke

Hebron was well suited for the temporary capital of David’s kingdom, being situated in a strong position in the mountains of Judah, amidst David’s friends, and withal having especially sacred associations (see the marginal references note). It appears to have also been the center of a district 2Sa_2:3.  -Barnes

Re David's Polygamy

David had his share of sin---the premeditated murder of Uriah and his accumulation of wives in general--six total at this point in 2 Samuel. In the Biblical Illustrator, W. G. Blaikie describes it thus:

"Though polygamy was not allowed to David, it certainly was winked at; it was not imputed to him as guilt; it ‘was not treated as an act of rebellion against God’s law. But, on the other hand, this toleration of polygamy did not and could not prevent the evils to which, from its very nature, it gives rise. There could be no unity in David’s family, none of that delightful feeling of oneness, which gives such a charm to the home. In his own breast, that sense of delicacy, that feeling of chastity, which has such a purifying influence in a family, could scarcely flourish. And further, as the absence of delicacy must have been characteristic of David, so was it also of his children; the unbridled passions of some of his sons gave rise to the most dismal tragedies; and left blots on their name that even time could never wash out."

David had much greater success in his public life than he did in his private.  It's a rare person who has both.  Perhaps the polygamy led to his indulgent nature toward his children, or at least, it would certainly cause the wives to pit their children against each other and spoil them in this way.  In any event, the polygamy has its consequences.

In our modern day, I think of multiple marriages and divorces as having many of these same consequences.   Whether God "allows" for these instances is one point, but another is that it almost always creates an environment of disharmony in the homes affected.  This seems like a natural consequence of the outgrowth of the choice to divorce and remarry.  Family life becomes increasingly complicated and fragmented.  It certainly lacks the unity of a one home one partner marriage.