Yes, lying is not the best way to go about things, but sometimes you have to do what you have to do. You could tell them you are going to the library, mall, park, or any number of places. You could even say that you are going to church with a friend if it is on a Sunday. Just make up a place that you are going to go at that time. You could even say you are going at nine so that you can make sure if they give you crap you dont end up being late.
Dont say you are going to the store because that wont give you enough time to see him, but a movie might.
Good luck and I hope everything works out. If you ever need to talk, please message me. I hope you and your boyfriend have fun.