Via The Verge:

…ultimately, the ending fits because it’s the necessary completion of a meaningful arc. The film is Michelle’s story. It starts with her, it sympathizes with her throughout, and it dismisses plot points that aren’t related to her story, or important in her character’s mind. It doesn’t end with Howard because it was never really about him. It’s about the long-term effects of abuse, and how one person overcomes them.

Great analysis. I really enjoyed this movie, including the ending.