It sounds like the daughter is just another possession you all are having trouble dividing up and who is getting lost in the confusion you all are experiencing in your relationship with each other.

I think you need to get your relationship sorted out before you can hope to raise a healthy daughter. It could be your wife is actually using your daughter as a surrogate for herself, is missing you or wishing she could express her anger at you for leaving or the relationship not working, etc. Whatever you all are trying to accomplish with multiple separations, I don't think it is working? Save the money up, get a/lawyer(s) and make it official or do marriage counseling, send the child to another relative for awhile or something!