Absolutely, yes.
However, it solely depends on the mutual agreement between partners, and the necessity of maturity of those involved.

If it is of the same goal of those involved with a shared understanding that this is what they want...I see it very possible. Open relationships are often practiced among people with such free-thinking attitudes, which is not only perfectly fine, but successful, as well. (There was a time that it was a practice of mine, as well....although have long since "tamed" over the years). I know it is very possible.

However, in your case and from what you have provided, I would not think this would be remotely likely.
You have far too many mixed emotions involved. Uncertainty is one thing that has no place in involvements such as this, as these encounters are purely based on the physical gratification.....and emotions (regardless of what level), only create problems.

It definately has to be a based on mutual concent with open communications. No room for indecisiveness or hidden alterior motives....otherwise it will prove disasterous.
I would definately refrain from venturing into any kind of open relationship with this person as there is obviously more there which you are attending to.

Hope this helps some.

Shangrala