Everyone is talking about physical escalation here when actually i think its both personality AND Physical escalation.

A guy who is forward not only touches the girl but also teases her, Questions everything she thinks is interesting, And makes light fun of her little flaws (with a smile obviously) Basically banter!

If your personality isnt matching with your escalation, maybe thats why theres no spark.

On top of that start to not give a fuck about the outcome.