What to do?

Amber • I have an amazing boyfriend and I`m 20
Hi ladies, this guy and I are in a long distance relationship so to speak as he lives in Pennsylvania and I live in Kentucky. I'm willing to give him a chance as we have made a plan for him to visit for the first time the week of my birthday, my grandma however has mixed feelings on the topic and it brings me down because she won't even really give him a chance and her only argument is "he isn't here". Me and this guy have known eachother for 3 months and hit it off instantly and we Skype and talk everyday. But I don't know why she won't even give it a chance and at least support me in this and let me find out myself.(he is 19 and I'm 18 by the way)