Stab away. God has and does many things we do not fully understand and probably never will. His capacity and intellect is infinite. The bible states that he will wipe away every tear and makes many other statements that lead theologians to conclude that obviously it will be impossible to be sad or have regrets in heaven. I do not have the capacity to explain fully how God will go about this. I will offer a possibility to illustrate the concept. It would be a simple matter for God to remove any memory of anyone in our pasts that is not in heaven. This would leave no possible source of sadness relating to this issue. There are many scriptures to lend credence to this concept. It records that many supernatural changes will happen when we are resurrected: we will have no desire to sin, we will be incorruptible, we will not have pain, fear, etc.... Since one supernatural claim is as improbable as another then either anything is possible or nothing. Non-believers make a common mistake of applying probability to different supernatural claims. They will accept some and deny others. When they are all equally probable. Did this help? A finite mind is at a disadvantage to describe the capability and actions of an infinite one. The bible suggests there will be no sadness and that is enough for me.
I will add that the depression and profound and debilitating sadness related to my mothers death was completely removed at the moment I was saved. If that is an indication of God's power then Heaven will be beyond comprehension or description.