Perhaps stopping all this spanking may be a good start, and certainly your boyfriend should not be spanking her It would be a good idea for you to be with her more especially as she also goes to day care, go with your gut feeling it does sound like there is some fear there., be aware for your daughters sake .
there could be another thing that's not behind you or your bf spanking her at all....i've talked to nearly 15 moms here in the houston area, every single one with no household the same, and they've had "horror" stories like this....come to find out, alot of these children went back to "normal" after being switched to another daycare! i know that sounds wierd, and none of these children even went to the same center, but a few of the children were having particularly hard times with the parent who was around the MOST...aside from "stopping all this spanking" you really might want to find out what's going on in all aspects of her life...if she has no problem when you're NOT around, then you need to kindly nip this in the bud, as when she gets older, it could turn into a "mommy will save me" deal, where bf or stepdad may discipline her, and she will come to you and you will "save her" from a punishment.....also, if you've been living together for a year, this person is NOT a stranger to her.....therefore him disciplining her is not an issue either.....my stepson is somewhat like this(well we're engaged, but i've been around for 4 years, and he is only 5).....and my stepson thinks that if daddy's around, he can ignore me flat out, or "tell" on me.....of course, when his mom and my fiance alerted him to the fact that i am also a "parent" of sorts, then i am also allowed to discipline....this has helped quite a bit. i hate to discipline him, and i don't spank him(for reasons other than not wanting to), but when daddy is around he thinks i'm crazy or he doesnt have to listen......
Me and my wife had this issue. When my stepson was 5. We have been together for 9 yrs and married 81/2 yrs. he is now 13 and he has been aware for a long time that i am his parent too. I am very involved with the discipline I do not spank him. i also don't get in involved til my wife calls me in. I do make rules and expect him to follow them. I have swatted him in the back of the head and said smarten up.
I believe its just a phase. this behavior with our son only lasted a few months.