That all depends on just what specific "impossible" situation it is that you are talking about I suppose.

Are you saying you are currenttly in a vanila relationship but want, or have, played and or cheated (if committed in mognogamy with the nilla) with a kinkster you have come across in the meantime.

If the vanila relationship a marriage?

Is the affair (if any) in real life or just some online daliance?

All these questions and more have a lot to do with what your reaching for or not.