Another girl

Hey guys, so my boyfriends neighbor has a granddaughter that is one year younger than us. She comes to town for a week a few times throughout the summer & Her and my boyfriend hang out a lot when she comes. They do stuff that personally I feel like him and I should be doing (jet skiing, shop, going to get breakfast, and he even has her sneak over his house late at night).. we both leave for college in a week and a half and she comes the last week we are both here. I have this horrible feeling and I’m so stressed that he will be spending more time with her than me on our least week together for a long time. I told him previously to just let me know when they’re together and last time she was here he didn’t tell me, and would not be texting me when they were together. I’ve told him again this time to out himself in my shoes, and that I understand they’re good friends but I have a right as a girlfriend to just know when he’s hanging out with other girls. Am I crazy for thinking that? I told him I’m nervous she’s gonna come and I won’t see him and bla bla bla, When I told him he just told me he understands but I got no reassurance that he will make time for me or anything. Super stressed guys, I have a horrible gut feeling. Idk what to do