It is her age.
Children, at various age junctures, get attached to their Mom.
It is NORMAL.
Kids, at different age junctures, also manifest and express this, differently, per their respective age.
its okay.
talk to her.
Carry on with your regular routines.... and don't cater to it ALL the time. But talk with her... and encourage her to do things apart, but in the same room with you.
Tell her everyone has a routine.
Get the book "The Kissing Hand." It is about going to Preschool... but you can use the book for explaining any kind of separation, from you.
Its a real cute book to read with the child.
Next: does your Husband, make time for her too???? What does he do with her during the day???
Maybe, she gets bored? Or is not, attended to, like a Mom would???
Have your Husband ALSO do her routines, with her.....
A Dad and Daughter... also bond too. It is very important.
But different than with a Mommy.
I have a daughter... and she is bonded with my Husband, too. But in different ways, than with me.
My Husband, nurtures her. Tries to understand her as a girl. Which is what Husbands need to do.
Some Husbands, don't know what to do with a 'girl' child.
Explain to your daughter, that you go, then come back.
And give her something of yours, as a Lovey.
My kids, even at their ages, LOVED my t-shirts that I wear all the time. They like Mommy's 'smell'...and they say I am so cozy... and having my t-shirt feels comforting to them etc.