Depression is a major issue that your wife will need to address. The haircut is probably just how it’s physically manifesting.
This is going to be a challenge in your relationship, but get over the hair and focus on your wife’s mental health. Be there to support her and try to get to the root of the depression. That probably means therapy and possibly medication. You’ll probably want to also get couples therapy to help explore new ways that you and your wife can work together and support each other.
You might be having issues feeling attraction because her personality is changing from her depression. It’s not just the hair, that’s just what you’re able to see and pinpoint.
This is your opportunity to step up and take care of your wife when she needs it.