This is a general entry. I'm not experiencing it now but I've the experience in the past. Once in our lifetime, we will or we must experience losing people we love. The most hurtful lost is when we love that person so much. I think each of us must beware that a Hello will be end by Goodbye. It just that we don't know how, why, when and where. We can't expect that person to stay forever. We must have this paradox that, "We can't fully rely on someone to make us happy". We can't expect people to do so all the time.
Whoever you are who may be stumbled upon this entry, who find ways to move on, who find ways to be happy again, just remember that you're strong. You still have others around you. There's no use to think about people who don't want to stay. Don't waste your time for someone who doesn't care about your feelings. Besides, that is their right to stay or leave and we don't have right to make them stay or leave. They're not the reason you live by the way. Allah has a plan for each of us. For someone who have left you, Allah will replace that person with another person. For the things we have lost, Allah will replace them with a new thing that we need.
However, I've heard about "Never blame people in your life. Good people bring you happiness, bad people give you experience". People come and go in our life for some reasons. Maybe, they don't expect to leave you that way but their admission into your life have left many things to be learnt. You can be strong, try to think positively and you will be happy because happiness varies from many ways. Just be patient and say Alhamdulillah for what you have now. There are so many people who want to see you smile. A smile can cure your sadness .