There are a number of issues here for your daughter -
she is at a sensitive age, as advised, and is exploring her reactions to various cahnges in her life.
I would guess that if you sat her down and asked her why she is doing this - and i don;t for a minute suggest that you do - she will answer with "I don;t know ..." which will be the perfect answer, since it is the truth.
Part of her baheviour is a little attention-seeking from you, to say 'I'm here as will you know!' when your guy is around, and part of it is seeing what his reaction is.
If he has said nothing, and appears to ignore her - which is the best thing he can do - then this will simply pass when she goets bored of the lack of response - pretty quickly I'm guessing.
If your guy is uncomrtable, talk it over with him, and ask him to ignore her - remember, the adult perspective on children's behaviour is very different - what he sees and thinks compared to what your daughter is looking for can be oceans apart.
Above all, reassure your daughter that she is vitally important to you - make sure you give her plenty of time, and be open and honet with her questions about everything - which should be encouraged.
As a dad of three girls, I have learned to keeo all communication channels open at all times, most of the time you get ignored, sarcasm, or drivel, but just sometimes she will need to reach oout, and if she is used to talking to you, she will do so openly.
Good luck.