There's a big difference in stumping your toe and dropping a motor on your foot. The level of pain is different. The level of damage is different. And hence, the method and length of healing will be different. Seems simple to understand when put that way, but we don't act like it when it concerns emotional pain.
Just because you can't see the scar doesn't make it real. We have to be careful to allow people to fully process their pain. It doesn't matter if we think someone should be over something by now. Our opinions are useless and can be counterproductive.
Processing pain involves a time period of grieving and yes for some, wallowing. Not everyone is going to go through their trials the same way, but the thing is to let them go through it with our support. Our jobs are to gently support and guide a person toward something better on the other side of pain. We should show them the light that is awaiting them when the process is finished, not time how long the process takes.
If you have, and we all have, hurting people in your life, don't judge them if they appear weak to you. You don't know what they've been through and you don't know how much it may have hurt them. And you also don't know how powerful they can be when all the hurting is done. You be an encourager and remind them that it won't hurt always. They won't feel weak always. Things can get better with time if they let it. But don't you dare make a hurting person feel guilty because they are hurting.