You approached a girl on the beach, chatted, flirted, then took her contact info. Then, as you were about to depart, she looked at you, hair fluttering about her face in the wind, shy, hesitant, as if she wanted to say something, or was waiting for you to.
You approached a girl on the train, chatted, flirted, and took her contact info. As you arrived at her stop, three stops before yours, she seemed hesitant to leave, pausing, waiting, leaving dead space in the air as she stared into your eyes.
You approached a girl at a bar, chatter, flirted, moved her a bit, and took her contact info. As you prepared to return to your friends, she fell silent, gazing at you, as if wanting you to do something other than what you were.
You took a girl onto a date, connected with her, laughed with her, bounced her to the second venue you meant to bounce her to, and finally moved to wrap up the date. Yet as you told her you had a great time, she got quieter, told you that yeah, so did she, then lingered, not leaving, not turning away.
When you encounter situations like these, where you've made the approach or taken the girl onto the date, yet she hesitates at the end of it, waiting on you expectantly, surprising you (because you expected a nice simple cleave from the interaction here), what can you do?
The simplest answer is extend the interaction... and see if you can't go further.