Why don't you like me?

As I've said before, I'm very close to my family. I have one cousin in particular that I'm very close to. Tony is like a brother to me. He is only 5 days older than me and we lived together for about 3 years in LA. After I moved back to San Diego from LA, Tony started dating this girl named Maria. Tony and Maria have been dating for abou 2 years now. I'm not a big fan of Maria, although I really wish I was. See, Maria doesn't really make the effort to get to know me, which bothers me since Tony and I are so close. If ever I was in LA, Tony and I would plan to get together to hang out for dinner or something like that. Maria would never come. One time I was even at their apartment and I thought she wasn't home. She was home. She just never came out of her room! I was there for 5 hours and she didn't come out once. At first, I was just like whatever. Now Tony and Maria live in Chicago. They fly out to LA a few times a year. When they do, my sister and I always make the effort to go and share a meal with Tony. Maria NEVER comes. I understand that she also wants to see her family, but she could at least get to know our family a little bit. One meal at least. She always come up with the lamest excuses too. The latest one she gave this past weekend was that she had to go shopping for a dress. We weren't meeting up for dinner until 9:30 PM. What kind of store is she shopping at that is open past 9?! When Tony first started dating Maria I was so excited for him. I was hoping that Maria and I would become close too. I hope some day this changes. People tell me that maybe she's intimidated by me, but I don't see why she would be. I don' think I've ever been rude or mean to her. I'm hesitant to bring this up with Tony. I'm afraid he'll get defensive and think I don't like her. Then he'll go tell her what I said and that will make things even worse. Plus, I suck at discussing uncomfortable topics. I'm the post non-confrontational person in the world.