I think that was a considerate way to not push herself on to meeting your kids in case you are uncomfortable or worried about the well being of your children meeting a new woman too soon
Next time around, and for me personally, I might not wait super long to introduce son to a new boyfriend. I need to see how boyfriend interacts with him and reacts to my parenting choices (cause if he’s like the last guy I will know to end things quicker). I’m wondering if she wants to make sure you are ok with him before she fully emotionally invests?