Does he has feelings for his step/adopted sister?

me and my partner are in in our early thirties and his adopted sister is in her mid teens. i just dont know, whenever he mentions her name i get this odd rushed feeling going through me. and i know im not insecure im the least insecure person there is. and his adopted sister behavior towards me is extremely odd its like she crushes on him and she just hates me cause im with him or something. he frequently talks about her which has nothing to do with our life or our goals together for the future.

if i talk to him about it will seem extremely odd on my part and make me seem crazy. i feel this situation is extremely complicated. iv had other relationships and they weren’t nothing like this.

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1 y
we have been together for like a year now.
Does he has feelings for his step/adopted sister?
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