Do you all know why she stopped having feelings?

I'm a 19-year-old guy, and I've been in a long-distance talking stage with an 18-year-old girl. Recently, she told me that she's lost her feelings and wants some space for a week. When I asked her why she felt this way, she admitted she wasn't sure. I'm considering what to say when she reaches out again because I can't shake the feeling that she might be interested in someone else while we've been talking.