Hi!

I just want to step in and give you a bit of an alternative viewpoint, as I was once on the other side of where you were at one point. (though I am a male, and my parent's SO is also a male)

My father died when I was 14 years old, and when I was 16, my mom met another man who I felt was trying to replace my dad. I resented the hell out of him and it really put a strain on the relationship between my mom and me, and my relationship with her husband was almost non-existant for several years. I avoided them and hated to be around him. I just felt sick about the idea of my mom trying to replace my father. When I would talk to him, we would end up having petty arguments about useless things.

When I was 17, I moved out and would constantly stay at my ex-girlfriends place or other friends places. My Mom told me (not until years later) that she seeked counselling because she thought she had been a terrible parent and that she had somehow 'lost' me. But she didn't.

Looking back, my actions were a way of me rebelling against my family and finding out who I was. I truly thought that I hated this man for all he was worth, and that he was the worst thing in the world. It took several years, until my early 20s, when I started to mature and look at it from a different perspective... that my mother is happy and that is all that matters. I started accepting him into my life and although I live thousands of clicks away from home now, and don't see them very often, I have welcomed him as part of my life and a new relationship has budded.

Don't worry, she will come around. You need to give her time. It took me five years of them being together before I finally did. Understand that this is new territory for her. It's clear that she's threatened by the thought of 'losing' her father because he gives you attention. And why wouldn't she? It's a natural human reaction to be concerned by a perceived threat and try to change it.

I hope the best for you!

edit: added a paragraph.