Hi Lou,
Yes, it’s a good time to give up on this.
She likes attention up until the point when a guy seems to be getting serious about her and then she bails.
She may have stopped watching your Instagram stories as fast as she used to, if at all, because she doesn’t want to expose herself to the possibility that you could make another attempt to get her to go out with you.
In other words, now that she knows that you are serious about her, she has bailed.
She may have showed up to that lunch date with the coworker because she knew that it was all about friendship and nothing more.
Thereby, she could handle that.
If her ex cheated on her, she may also be dealing with trust issues when it comes to relationships.
If that ex is now trying to come back to her, she may also be debating whether he is worth it.
All in all, she doesn’t appear to be someone who is seriously looking for a relationship with anyone at this time.
The attention that she receives from men is enough.