My wife and I are in our thirties. She is the "godmother" of a nice 8-year-old girl (her sister's single child). As her husband, she has become increasingly interested in me lately (I'd say since about a year of two maybe), to the point that she spends a lot of time with me (hugging, playing, showing me stuff on her phone, sharing "secrets" etc.) whenever we're all gathered at her grand parents' place (my wife's parents). 

It is very nice and I surely like it but I find it quite surprising because she didn't use to like me before (she was rather shy actually and avoided me) and also because I am not sharing the same native tongue with her (them, i. e. my wife, my wife's family and obviously my little niece are from another country than I am). By the way, I know well enough "their" language so that she can understand me and so that I can understand her without any problem though.

Anyway, I am wondering if this is a phase and if this "attraction" towards me will probably change (for example, as she grows older, she may then get closer to her aunt to talk about more "girly" stuff)? I have the "feeling" that it could be something that as a little girl she might be "attracted" and interested in males (maybe something with hormones or so, even if for her age it might be early). Maybe me being a "foreigner" makes it more "exotic", maybe she finds it easier to get my attention (I am almost ok to play along with her, etc.). Just to be clear, I don't mean anything sexual by "attracted" or "attraction", but simply "great interest".

I am also interested because it creates some kind of "jealousy" from other family members, like my wife, or even her own father, who envy my position of being kind of "the favorite". I am honestly not trying to get all her attention, I am honestly not trying to be the most important person for her or something like that, but I just enjoy spending time with her and always try to take time to play with her, to interact with her and so on.

I'd like to hear about your opinions on that, advices, suggestions, experiences, anything that you think could benefit her, me and the relationships among the family (especially regarding jealousy or people feeling left behind).