Am I in the wrong?

Hello I’m 19 years old, and I have a little bit of a dilemma. This is about my Mom and her boyfriend. Anyways I’m going to start from the beginning. In 2016 my father passed away from cancer. My mom has been widowed up until a few months ago. She asked for my ok and I’m 100% for it, it’s not my life to live it’s her I don’t even know why she felt like she had to ask. I’ve met the guy 2 times and actually really like him. My mom a few hours ago told me we are going to dinner with him 2 weeks from today so he can get to know my sister and me better. But apart of me doesn’t really care about going like I rather be out hanging out with my friends. My whole thing is that I really don’t think I need to get to know him like that. As long as my mom’s happy I’m fine he seems to treat her well. I told her that apart of me feels like I don’t need to really get to know because it’s really between her and him. She said I was being ridiculous. Am I wrong for this? I just don’t really have any real interest.