Regarding a name change, the mods will permit that (or “have permitted” that in the past) if the request is made politely by a member in good standing. It wouldn’t hurt to try. It’s a process that you cannot do on your own.
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As to the advice from @stanleybmanly regarding “the reason she is away for so many hours every day”, only you can determine how likely that is. Personally, when I was much younger and more driven in my career, I spent many hours at work, too. In my cases there were several reasons:
1. The demands of the job on a young person with a certain amount of ambition and/or pride;
2. Overtime, when it was available – even sometimes when it wasn’t well compensated;
3. Not wanting to come home to a wife who frequently whined about my long hours. (Though you don’t know me and won’t care, over the course of a long marriage I was never unfaithful to my wife, no matter how often I was tempted / attracted, and no matter how jealous she frequently became that I “must be unfaithful, because every man is”. Not. Even. Once. That did not mean, though, that I was always happy at home.) So, it comes down to your assessment of her character: do you think that she’s really working all of those hours, or is there more going on? I can’t say “your gut will tell you”, because apparently my wife’s gut was unreliable.
So I would suggest that you do whatever you can and as often as you can to make the house – and yourself – as appealing and as pleasant as possible for her to return to. That includes “keeping yourself up”. (I’m sort of laughing to myself over the things that I’m saying to you that I never would have dreamed to say to my own wife at the time – but which totally apply.) Be interesting as well as interested in her, keep complaints about anything to the least possible amount, and obviously take excellent care of your daughter.
But @elbanditoroso and @Cupcake have potentially good insights, too. Although my wife and I had the same kinds of pressures in our marriage that you seem to have in yours (although with the gender reversal), and although we generally got along okay (at least from my point of view; I found out from her much later in the marriage that there were things about her unhappiness that she did not tell me about, and which had a detrimental effect on her, obviously, and on us as a couple, too), when we did have fights she would say the same thing about retaining custody and making things difficult for me.
In my case I knew that that was generally “just talk” that only appeared at times of high stress or upset, and everyone has those. You’ll have to assess her, because we can’t, to know how much of that kind of talk she really means. If you think that she does mean it seriously and in any way enjoys the effect on you that that kind of talk has, then definitely make defensive plans. Quietly.