Dear Abby: I love my friend but can’t handle spending extended time with her on trips 

Dear Abby: I have a friend whom I love and enjoy being with. However, when we spend extended periods of time together, such as a few days on a trip, it doesn’t work well because of our personalities and belief systems. She is not aware of the struggles I have when spending more than a few hours with her and regularly invites me to go on trips with her. I have put her off a few times without telling her the truth. Is there a polite way to tell her that I’d rather not go on a trip with her?