Stop reaching out to them. They could have things going on or they could just not be in the space to talk at all or specifically to you. There is no way of knowing. However its okay to reach out a few times to someone. After the ghosting continues, just go on. I know it sounds super harsh that I wouldn’t encourage you to chase people but in 2018, give people space to process their lives. The ghosting may not be about you but there is no reason to chase an adult around for any reason. You can always pick up with a person if they had stuff going on that prevented them from being a good friend. When you see that adult being super cool with another person in the midst of ghosting you, than just leave it be. Who is supposed to be in your life will be. I also belief in provision. If you need a friend and you continue to be a good friend, God, the universe etc. will send you what you need to replace. This is why I always believe you never really lose friends. So acknowledge how frustrated you are and then release that person and the relationship. Also do not feel obligated if you see that person in person to do more than a hi and bye. You don’t have to do acrobats to get that person’s attention. People are allowed to process life, go on in life, befriend who they need to. You also have every right to continue on in your life and be at peace. Part of peace is about preserving your spirit.