Once Morrigan has joined your party and you have seduced her
there are more dialog options than usual. The "Kiss her" option falls in the exact same place as the Done option for a normal companion. So my muscle memory as a player going thru the ritual of distributing loot among companions gets mapped to an instinctual action for my character, stealing a quick kiss in the middle of the day to day routine. It has surprised me how much this has done for my immersion and my attachment to this collection of bits, I can't imagine the placement was accidental, and I want to congratulate whoever wrote her dialog menu on a very subtle insight and wise choice.