Hmmm.....you must excuse me for pointing this out, but there is a piece of Zelda fanart I am familiar with from one of my favorite artists on pixiv that this does resemble a little too closely to overlook mention of. Please see below:
So I must ask, does your wife often use other people's artwork as direct references for her own? Now, I think it's great to use other art as a source of inspiration, but I don't think it's a good idea to imitate something too closely if the work is intended to be an original piece you mean to claim credit for yourself. If someone else can recognize just by looking at it that other art was probably used as a reference and not mentioned, it's not the best sign.
However, I mean this speaking as a general practice. I understand that your wife probably just wanted to do some art for the two of you for fun and likely didn't intend anything more than that. I actually just mean to say this as a general tip in the future though. Otherwise, I hope she continues her work, and you both continue to enjoy it.