Home Sweet Home?

I seem to be losing my father and sister. It changed ever since 'she' started staying at my dads with her five kids. I didn't seem to like her in the beginning, as well as my sister, and I am still on my way to getting to know her better. My sister, I believe, had moved to her side. The longer 'she' stays, the longer I drift away from my dad and sister. We used to try making plans together; all of us (me, dad, sister). Not just everyone (dad, sister, 'she', and her five kids) excluding me. He used to care. He used to make me "check-in". Now it's as if I'm invisible. I basically live at my boyfriends now throughout the day, and sleep at my dads for the night. That's how much we've drifted apart since all this, which happened only about a month ago. It's like I never existed to my dad and my sister. As if my dad and 'she' have always been together. It's not going to last between them. My dad can never keep a relationship, and they both argue just like my dad has with every other girlfriend he has dated in the past. But why is this relationship lasting longer than any other he has had? Is it due to the fact that I don't like all this? That I don't like the screaming kids at 10 at night and 7:30 in the morning? Maybe she wants another kid? Or maybe my dad wants to get her pregnant so it'll be another kid without a dad? He does everything with them, -EVERYTHING (bowling, dinner, games)! Do I just want to gain back that attention that I once had when I was three? I do. I do want that attention again. I miss my dad. I miss him.