When she added her breast to the fray, she further enticed his curiosity and pleasure.  She was helping change his own definition of sex; perhaps lovemaking would be a better word for it.  Thoughts of how else he could use their bodies further aroused him, bringing him near another climax along with intoxicating motions.  “Risa.. I feel alive again being with you.”  This is the last thing he manages to say before ejaculating; not knowing if down her throat is a good place to dump his load.