My reaction is a clear and resounding "Hell no!" pardon my unprofessionalism.
The argument that stuck out to me the most was someone saying that "it takes two to make a baby" and that Alice was as much responsible for her "trouble" as he was, and this somehow justified him being able to leave/murder Alice.
I don't buy it.
It takes two, right? So Alice getting pregnant wasn't totally his fault, but it was at least half his fault. Those who are arguing that he should have been able to leave her to move on to Angela aren't recognizing his responsibility here. Already in the culture at the time, an out-of-wedlock pregnancy laid all of the risk and retribution on the unfortunate mother, and none on the father. A man who fathered a child with an unmarried girl could just move on and no-one would be the wiser; it could have almost no impact on him. The single mother, on the other hand, would have been fired immediately, and probably would have been unable to find work in her small town. She would have been ostracized from society until her only recourse would be to move - if she could afford it with no job and a newborn baby. Even if she moved to a place where nobody knew of her shame, her child would be there to show everything, like a scarlet A.
Most likely she would have had to lie and say she was a widow, or return to her family. Even these days we hear of girls being thrown out of the house for getting pregnant; do you think it would have gone over well in the 50's? She probably would have never been able to get married - single mothers were not desirable in those days.
George basically decided that his own desires were more important than not ruining a girl's life. Sure, she had her part in it, but she had so much more to risk. Her insistance that George marry her is frustrating, of course, but it is understandable. If George doesn't marry her, her entire future goes down the toilet. If George does marry her, well, he doesn't get the super gorgeous rich girl, but will probably live a perfectly tolerable life. Boo hoo.
What he wanted to do, even if he didn't mean to kill her at the end, was unforgivable. He doesn't get to be a karma houdini and get away scot free.
That said, I don't think he murdered her. What he did do was arrange the situation that ultimately lead to her death, unintended though it might have ultimately been. In my understanding, that's manslaughter. It shouldn't have sent him to the electric chair, but it shouldn't have sent him off to enjoy his ill-gotten pretty new wife, either.