If 'dating' is only defined as a sexual relationship prior to divorce, (which isn't Biblically condoned before marriage anyway) then we could claim any relationship as 'only friends', yet spending time and investing emotional energy into a friendship.
I believe there needs to be caution here, and do we really need to determine motive if two are seen as a couple routinely.
I see alot of Christians openly date, even in church -while going through a divorce. Is the church responsible to hold accountable these actions if they know, especially if someone is serving at church or on staff?
I gently advise to not blame one person for choosing wrong.
Deception is often very charming, and manipulative.
If, however, you mean "date" as in going out with someone who has become your significant other emotionally, or hoping to find out whether that person is a potential future spouse, then I would agree that this is not biblical.
Someone who is looking for a future marriage before the current one is legally over is basically cheating on their legal spouse, in my opinion. If divorce legitimately severs the marriage bond in God's eyes, then remarriage would not be called adultery since adultery is the violation of the marriage bed. " Perhaps in the name of grace and mercy we are failing to take a strong stand on the issues. We are to turn one another from sin, to watch out for one another, to hold one another accountable and call one another to repentance.
I firmly believe I have Biblical grounds to divorce, and don't feel the need to talk through my decision to divorce, as I am at peace with it and sought Godly counsel- but am open to respond to questions.