Here are some interesting thoughts.
First, some things, which are not clearly delineated in Scripture, are a matter of personal conscience.
Second, we do not have to let ourselves be dominated by the “Christian culture” of years gone by. I know the Bible tells us to not be conformed to this world, but there are times when we also conform to the mistaken teaching of those Christians who would impose their killjoy legalism on others. Yes, if the Bible says it is wrong, then avoid it at all costs. But some teachings have no clear foundation in Scripture, and can be safely ignored. Jesus reserved his strongest condemnation, not for those who enjoyed solo sex, but for those who imposed unnecessary religious restrictions on others.
Third, the Word of God tells us to “not condemn ourselves in the things which we allow.” (Romans 14:22) Or, as the New Living Translation says, “Blessed are those who don’t feel guilty for doing something they have decided is right.”
Therefore, if Solo Sex is a blessing to you, and if you are convinced before God that is does not violate Scripture, or Scriptural principles, and if you are doing it in a way that honours God, then it needs to be done with a heart of rejoicing for the wonderful gift that it is!