Sounds like your child is craving family time
Unfortunately, properly integrating new "parental figures" is difficult. Whether SweetLady wants to be that or not, she'll be seen as such by kids. May be a welcome or unwelcome figure, but nonetheless, that's how she'll probably be seen.
In this case, the child is, apparently, seeing her in the "unwelcome" category.
My partner and I worked very, very hard to build a relationship between me and the kids, before they were exposed to seeing any relationship between me and the father. So they in fact are eager to see me and wish I was around more.
Since you, and trust me, I understand how hard this is, have not quite set it up, you'll have to take a more direct approach to make your daughter comfortable. Fortunately, she's old enough to understand romantic relationships (or starting to be old enough to learn, at any rate). I think the best thing you could do is have all of you sit down and explain that daddy loves both of you, and that he is, whether or not the daughter sees it, meeting BOTH of your needs.
Then, maybe ask if she would like a little more time with just you and her father. And, at some point, sit down with her and say that SweetLady is an important part of the family and, ask your daughter directly, "How would you like to build a relationship with SweetLady? She'd very much like you and her to be friends." Could be met with resistance, but if your daughter is reassured that all is well and that the dad is not replacing you with a new mom, I think she'll be fairly open to developing a new relationship with SweetLady.
I would hope, that way, your daughter feels an active part of this, not having someone forced on her, and will feel better that her parents are in a strong, stable relationship. That this is about enhancing the family, not changing it. Right now, she's probably just scared. I think she probably just needs reassurance and explanation.