She's grown out of "dating for the sake of dating."
These girls are not into wasting their time or energy on a guy they really can't see themselves being with long term. Casual dates just seem like a waste of time. It doesn't mean she isn't interested in dating, she's just not interested in attending ONE more mediocre date. Mediocre dates happen solely for the sake of going on a date. This is a concept that has grown tired on her. She would rather have a good gym sesh, some pinot noir, a face mask, and bed by 9 p.m. than participate in a forced date. She's become picky, but if someone worthwhile came along, she would be on a date in a heartbeat!