You don't have to be with anyone. It is perfectly possible to be alone without being lonely. But you should get out if only to get some fresh air and exercise.
Grief can take a long time to wear off, indeed it never does wear off entirely. For the first year after my wife died I cried every day. Now nearly eight years later I often go several days without consciously thinking of her and then some random event, sight, sound, scent, etc., will remind me. Then I have a few moments of loss but life must go on, especially if you have other relatives and friends.
One day you might meet another person you want to spend your life with, but it's not compulsory to have a long term living together relationship so don't feel pressured.