I suppose "negotiable" wasn't sufficient to convey my thoughts. The emotions associated with flirting and the mutual feelings you both have seem to align more with the Two of Cups. It captures the essence of talking, gazing into each other's eyes, and the stirring emotions within.
On the other hand, the 3 of Pentacles suggests that he envisions elevating things to a higher level. Moving beyond the flirty stage, where you both experience that stirring feeling, and transitioning into a more constructive phase, indicating a desire for a genuine and substantial relationship.