My partner seems to discipline my 3 year old daughter but not his 10 year old son. It really upsets me as sometimes his son can be so rude to him and just gets away with it. He’s a massive push over when it comes to his son and I hate saying this but it makes me dislike his son at times. 

When we don’t have his son and it’s just me, him and my daughter things are great but then everything changes when his son comes. His son doesn’t even like to share with my daughter most of the time and my partner then makes excuses for him!