Best friend suddenly wants to hang out with me again?

For the last 9 months, my 17 year old best friend has been dating a guy, and she slightly obsesses over him - she always manages to talk about him a lot. I have a boyfriend too, but I don't talk about him as much as she talks about hers. I used to suggest going to the movies/go shopping/go bowling etc with her once a fortnight, but she would always back out at the last minute to see her boyfriend, and I just gave up with her, and I didn't bother meeting her. I understand she wanted to meet him, but she would always cancel our plans at the last minute. She would also text him at college during free time, leaving me standing there like an idiot (as we usually hang out on our own during free time). It's been 7 months since I have met up with her outside of college, and for the past 3 weeks, she has constantly been suggesting 'girly' things we could do together, such as a sleepover, going swimming, DVD marathon etc. As far as I know, they are still dating, but she doesn't mention him or text him as much as before. HOWEVER, the latest event she has suggested is that we go and see a movie next month - and she let slip that she can't go with her boyfriend as he is going with his sister - I feel like she only wants me to go to the movie because she doesn't want to go alone. Is she trying to make amends for ignoring me a few months ago? Should I agree to go with her, both to the cinema and to her potential sleepover? Thanks for the help.