Yes. I have maxed out the 'intimate talks'. I will note that I need to increase the affection bar during a date before she will reciprocate a kiss -- she still rejects them sometimes, which seems different from some other slaves whom I was able to get to Willing. 

Turns out that it was her Tame factor! 

My strategy going forward will be Dating the girls until she reaches Consent:Developing, then trying to max all of her sex skills (oral, penetrative, etc). If that doesn't work, Date her some more and stuff. It worked out for me.