I met my plate about 9 months ago and we was seeing each other on and off for about 3 months before she got a boyfrined. anyway I guess they split because I asked to hangout and she invited me over. after talking for a bit I told her lets go out back and smoke (I brought a joint) everytime I've ever been over shes sat next to me outside this time she sat across which was odd, after about 10 mins I told her lets go watch a movie. I sat down and moved the pillows so she can lay next to me like she always does and she just walks past me and sits across from me. I told her she was far and to come over she replied saying "My blankets over here" I said bring it here then and she just turned and kinda ignored me. the movie played for about 15 mins before I got up and said I had to leave. She asked if I was okay to drive and I said yep and haven't spoken to her since (That was last weekend)

Why would a long term plate randomly act like this after inviting me to her place to watch a movie? I'm thinking she doesn't want to think she's "cheating" on her ex in the off chance they get back together.