I vote purpose. Somehow, some way all that we go through is preparation for something that is coming up ahead.
Life is long. You can fall in love at any time. The only people who can go through life alone even if they want to have to consciously decide to and make efforts to do so. Try not isolating yourself and be around people. That should work.
I do not think that anyone was meant to go through life sad lonely and alone, I think that is why there are more people alive, other than us. I could say that if I was alone and no one else existed but that isn't true.
I could sadly say that if someone has believed this is true for their own lives then I pray that God would touch their lives with His love, which lets them know that they are not alone when others are hurting them, that they are loved when everyone hates them without reason and they have a real purpose, if they live for God/others, unselfishly, in this world.
If life has no purpose then no one is "meant to" do anything. Being sad or happy is up to you.