ok, i would like to think that if you wish to have a r/s with
the fellow, it would be only 2 persons. Not with 3 or some phantom
lurking in the background... It would be more complication.
Aside from that, you let him kiss willingly. Did something happen
to have him kiss you? Why did you go on dates with a guy who is
already attached? What do you want from this guy or this r/s -
friend or stead or partner or etc.
You see, you have not included much info, the questions will get
you, the straight-forward person, more muddled... We only tell you
advice as per your description of the situation...