Jesus does have strong stances on divorce (Matthew 19), but he does provide instances in which a divorce is acceptable. Whether the divorcee has followed a biblical path to divorce or has not, we can't assume. We don't know their situation fully. Perhaps they've escaped an abusive relationship. Perhaps their partner committed adultery and they feel a lot of shame in sharing that information. Instead of assuming they did something wrong in the situation, hug them and comfort them.