Boyd would have never dimed on Ava like she did to him
Right before Boyd is arrested, he asks Ava why she did what she did despite having all the money in the world and she says she did it because she just did what she thought Boyd would do in the same situation.
This is not true. There's no way in hell Boyd would have betrayed Ava like that. He did some despicable things and betrayed some of his closest allies, but he truly loved Ava and I just have a hard time believing he would have ever dimed on her the way she did him. I think this was just a copout excuse for her utter betrayal of the one person who loved and cared about her. His reaction to her "death" despite everything she did to him is the most telling sign of this.
Also for the record, imo, she did not deserve the happy ending she ended up getting. Rayland should have hauled her off to jail considering she was Boyd's right hand woman in some of his more nefarious crimes. That was one thing about the ending I didn't like.