Should i just ask her out?

Ok, so i really like this girl. I think about her alot. And she really seemed like she liked me and was interested. She didn't say that directly but that's what it seemed like. We talk alot, and text a bunch, like everyday. Sometimes I text her first, and sometimes she texts me first. We are so sweet and nice to eachother, and it just seems like she really likes me. But idk, because she's been liking this other guy but i'm pretty sure they aren't going out anymore, and aren't going to again. And i went to to the movies with her and her friend, and my friends. It started off good, we sat by eachother and talked and stuff. But then out of nowhere she stops talking and switches seats with her friend and i end up not sitting by for the rest of the night, which sucked. I'm kinda stressed cuz idk if she likes me and if i should just tell her that i really like her. but i dont want to mess up our friendship, cuz she is a really cool girl. now usually she is really sweet and joking and cool and puts smiley faces when we text eachother, but the last couple of days, she hasnt been like she usually was. i just dont get it. did she lose interest in me? about half a week ago she told me that i was the nicest and sweetest guy shes ever met and that im caring and funny and that she just loves it. i was sure she liked me when she said that. but idk now she doesnt seem like it. did she suddenly lose interest in me? or maybe she just liked another guy, and was just nice to me? idk i really hate this and i just want her so bad. any help with this, i would really appriciate. thanks