I will go against the grain here and disagree with the 2 comments above. I don't think her reaction is necessarily a red flag. It could be simply that she is trying to respond in the kindest way she can i.e. she can't reciprocate your feelings and if she out-right rejects them/you, she runs the risk of stopping or blocking the exploration of your feelings. Did she ask you to elaborate or did she seem awkward and change the subject?

There seems to be a taboo on here about therapists having feelings for their clients. I can't see anyway for therapy to work without the therapist also having feelings... love, hate, jealousy etc. So it's quite possible she does feel something for you, she might even fancy you but if she is a good therapist, she won't act out on it.