Hello! So I know I'm most likely to get backlash for this thread. I'm just really hoping there is someone out there who can tell me it gets easier!
I've been with my partner for 5 years now, he has a 9 year old DS and we also have a 3 year old DD together.
I am really struggling with being a step mum, I always have..but just seem to be struggling that bit more recently. His son isn't a naughty child in the slightest, he's just a normal child who has his ups and downs, bad days and good days ect which I completely understand - we all have them right?! I just really wish I could click my fingers and feel more for him then I do 
When I first met my partner he had his son 1 night a week, alternated between Fridays and Saturdays, this was perfectly fine and I enjoyed the time we spent together. Over the years it's grown to every Friday - Monday so now 3 nights a week. I just struggle with this which I can't help. I can't cope with the clash of parenting styles and where the line is for how much I get involved, I struggle that I can't lay down the same rules for his son that I do for my daughter because then I come across as the evil step mum who he resents (I've tried talking to my partner about rules which he sticks to for a week or two then resorts back to how things were before) he is a good kid but like all children there are things he can do and one of them is to constantly put my daughter down, he never interacts with her and he ignores her 95% of the time when she tries interacting with him and there has been times when my daughter has said that he has said some really horrible things to her when we haven't been in the room, he always denies this so we never had any clue who is telling the truth as it's a he said she said situation - I guess from a parenting point of view I struggle to see that every weekend when my daughter is OBSESSED with him (literally counts down the days in the week till it's Friday and he's here again) then he can't even give her a hug back when he comes through the door. BUT saying this, he's a 9 year old boy - I know this isn't out of the ordinary? Another issue i struggle with is the screen time that is allowed, this has been an ongoing issue for a few years now and it always comes back to him spending all day on a screen (sometimes more then one screen at a time), he has so many devices and he gets upset when you try to limit it, yet me being the one to always enforce it I'm fed up of coming across as the 'mean' one when it should be his dad doing it! This situation I solely blame on my partner as he should be stepping up - but my partner works really hard in the week and so likes to have some time to relax during the weekend, his argument is that 'what else is he supposed to do?' - I do understand this to an extent, but what did 9 year old boys do before electronics? He's got books, arts and crafts, drawing and figures ect here that never get touched.
I like to think I'm not a bad step mum, I never ever let on these feelings no matter how frustrated I am, I never allow him to feel pushed out, I show him just as much affection as my daughter and if I'm honest I let him get away with hell of a lot more too! Anything I buy for my daughter I buy the equal for him too, I buy all the Christmas presents and I spend exactly the same amount on them both, I buy him clothes, I've paid for us all to go on holiday end of May ect ect - I just wish with every inch of me that I could shake this feeling I really really do, I wish I could create more feelings towards him but if I'm honest I don't think he would be bothered anyways. He is a huge daddy's boy and loves it being just those two, which is obviously still fine.
I would never ever try to lesson the time he spends with his father, he enjoys spending every/all weekends with his dad and my partner would not have it any other way. I've just found myself in this rut where, it sounds horrible to say, but I dread the weekends and I honestly believe it is making me depressed. This isn't his sons fault, his son was there before me, these feelings have just got worse since we had our daughter because this is when I started to struggle with different factors.
I guess I was hoping to ask for opinions for what someone else would do in this situation, I can't help but keep thinking about leaving - but then I break up my family for my own sake when everyone else is happy. Do I suffer in silence and just get on with it?
(Please don't be to harsh on me, I'm not hating on SS, I know these are my own feelings I need to deal with and I promise he is always made to feel welcomed and that this is his home!!!)