I feel lile noone acknowledges this enough

It happens to me alot where i have this feeling of wanting to push ss away, despite him sometimes being nasty and acting exactly like HCBM i see posts on here of other steps particularly stepmums with this over bearing feeling of wanting to push the stepchild out of the way specifically when a new baby is born, i think we forget its in our DNA we are animals so many of us struggle on here but i have noticed an increase in stepmums rather then stepfathers (not saying they dont have issues) i think it's unnatural and absurd to try abd play happy families at times, i dont know what are people thoughts on this? i act accordingly and don't show any signs of resentment but i think biologically this is normal i know their are exeptions people loving their sks truly and deeply which is great but i think this is also a common feeling. Something that reminded me of this and made me want to post was anytime i leave SK with my daughter 14 months while she is sleeping and i say dont wake her i come back and she is mysteriously awake and he has this big grin as if to say haha now it may be a coincidence or i could be plain paranojd as his mum is always out to get us but i dont like it i feel uneasy about it i feel he is trying to upset me but i dont know why hes like a fly in the ointment at times and this is how being a step parent really feels, i also think when you are breastfeeding your protective instincts go wild!