Isolation

In Genesis 19 God destroys Sodom and Gomorrah but saves Lot, his wife and 2 daughters.
Though his wife looks back, though the angels told her not to and she becomes a pillar of salt and is out of the story.
Originally, when the angels tell Lot to flee, they tell him to go to the mountains. But he negotiates to go to the small city of Zoar. The angels agree and only destroy Sodom and Gommorah after Lot arrives in Zoar.
However, after going through this trauma, Lot starts to make decisions based on fear and decided instead he should live in the mountains. Maybe he thought he shouldn't have bargained with God as God knows best. Though it is not clear that God wanted him to spend a lifetime in the mountains, just to go there for safety during the sulphur dispersal.
But he does go live in a cave in the mountains with his daughters. And the next bit goes on to show the dangers of isolation. The daughters get Lot drunk and get themselves impregnated by him.
I think Lot's story shows us that it is not good to move in fear and also that it is good to live in community.

In Genesis 20 Abraham pulls the same half-truth that he used earlier in Genesis that got him in some trouble- that Sarah was his sister and not his wife. It was fear driving this decision as well.
The devotional book that I am reading along with indicated this as a moral failure on Abraham's part. It also suggests that the lie was easier for Abraham to do the second time as he had already convinced himself that it was true.
It does suggest why repeated sins occur. One reason is they are probably our weak point. The other is that we tend to rationalize things and if we've done them once (even with a bad consequence) we may be more prone to doing it again.

May we be driven by love and not fear in our decisions