Billy's parents clearly detested one another, so why didn't they get a divorce? Mr. Lenz could have then sued for custody of Billy, which he could probably win since even a blind person could see that Mrs. Lenz hates her son and wants nothing to do with him.
- She wasn't exactly a bastion of mental stability, and the impression given is that she hated Frank (her husband) and Billy with every fiber of her being. Maybe she also wanted to milk sympathy from making it look like Frank had simply "run off with the boy" or something. We also didn't see or hear the entirety of the confrontation, it's possible that she did plan on simply leaving but things somehow got out of hand (their incredibly shoddy disposal of the body and the fact that they didn't kill Billy too indicates that little to no thought went into the murder). As for Frank himself, well, it was 1975 and maybe he was resigned to the belief that he wouldn't get sole custody Billy, and he didn't want to risk leaving him alone with his mother (who, for all we know, could have acted entirely normal in public) for any length of time.
- And actually it wasn't until 1969 that 'No Fault Divorce' was passed, making it easier for couples to split up if they simply weren't happy together. And even then, the widespread belief was in upholding the image of a nuclear family, especially if there were children involved; people thought it was better to stay in an unhappy marriage than put the kids through the trauma of a nasty divorce. It wasn't until the end of the 70s that attitudes started changing to more liberal views (they called this the Divorce Revolution). It's also possible that the two of them simply grew up in conservative households and didn't see divorce as an option.
Are all of the photos Claire keeps in her room of her, Leigh, and their mom, or are some (like the blonde baby with fake teeth on her pacifier) of Leigh and her family before her divorce or Claire and a younger sibling?
