AITAH for not responding to a friend due to dry one word responses?

I love my best friend. She's always there for me but it's a reoccurring thing where she gets oddly distant. I try my best telling her about my day and asking her questions, encouraging her with work and school but times like now she just leaves me hanging it feels like.

It feels very confusing because other times it's perfect. We are best friends and our conversations flow perfectly.

I ask her if she's okay and she says yes, but it doesn't feel okay? Days pass and then its back to normal but then the cycle repeats.

It just hurts because I won't respond out of frustration then she ends up messaging me asking if I fell asleep or something and I don't know what to say at that point.