I always thought that Genesis 16 is one of the few times that Abram wavers in his faith in God. He tries to fulfill God’s covenant by his own means is what I was always told. But I don’t think God mentions anywhere that this seed of Abram’s would come from Sarai. So maybe he thought that this was the way it was supposed to be done. This may seem wrong to us now, but the only other instance God mentions marriage and how its handled before is with Adam and Eve. The whole population has been destroyed since then and so maybe Abram didn’t know. Either way we know from the outside looking in that this was not God’s intended method for the continuation of Abram’s line.
I don’t know exactly what looking at someone with contempt is like, but it is enough for Sarai to tattletale to her husband, even though she is clearly the initiator of this fiasco.
We have here the very first appearance of the Angel of the Lord. Not really sure if this is actually the Lord or if it is an angel speaking for the Lord. He speaks as if He is God, yet other times He speaks as if doing it in the place of God. More about that here. You can’t read what the Angel of the Lord says though without thinking of the Middle East conflicts now. I am amazed at how many things in this book about the first years of earth, still resonate and have effects in today.