I know I am, I feel I am yet I can't help but feel annoyed when my partner tells my LO off 
We've been together 4/5 months and he's around my LO every day always playing with him. My LO loves him! Don't get me wrong I do to. We've moved fast but that's how I want it and I've never felt this way about anyone
Like today we went to Argos to pick his PS4 up whilst we where there LO being 18 months old and being just woken up was wanting to be held as soon as the woman comes over to him he's like "you can hold him" we'd been in the store 2 minutes and all he had to do was stand there and answer question. After 10 minutes LO gets a tad restless as he like to run around and he can't. I sit him on the side and every time he makes a sound or goes to touch something he just looks at me with that old "why can't he keep still and be quite" look.
Lo was touching the little charity pots on the side (the ones that have the slot in and are chained round the chip and pin machines) and he starts going "don't touch that" or "Stop" he's 18 months old he's not robbing them literally just touching them and putting the tip of a pencil in there and taking it back out again. He accidently knocked it off the side and my partner caught it so he looks at me with that look again and goes "see what happens when you let him play with things."
So I'm there trying to hold his arms away from anything he may find remotely interesting and keep him quite, which is VERY hard with my LO.
We get home and he starts all over again because LO is touching the box to his PS4 and the controller?!?! Seriously it's new he's excited he's not exactly going to pick it up and chuck it out the window is he!
I've been a Lone Parent since I found out I was pregnant and with my LO everyone always follows my orders down to the 'T' when it comes to my parenting but I seriously can't help but feel annoyed if someone else tells him off and I don't know why. If he's done something wrong believe me I'll come down on him and he will give you a kiss and a hug for a sorry.
How long did it take you all to get use to your partner telling your children off?