I agree entirely with this. If my daughter tells me she has missed me while she has been at nursery then I will say that I missed her too, but then usually follow with a line/question about what fun things she did at nursery etc to make sure that’s the focus. Same with missing Daddy at the office - we miss him because we love him being here, but in the week he works at the office.There is nothing wrong with saying it, if that’s what you want to do.
I have personally never said it to my daughter (4) as I don’t want her to start thinking she might miss me when she’s at school and therefore doesn’t want to go - that’s just me though, i don’t think it’s right or wrong to say it.
I think the issue here is because it isn’t ever shown in a balanced way - Nini and Rebecca are besties who must ALWAYS be together. Plus Nina only recently was wobbling about going.
You will know if you have a healthy relationship with your child and I’m sure you do!