Spending quality time with other people, perhaps animals as well, time spent alone won't fill the void from being alone. Movies, books, video games, sports, daydreaming, porn, even music will lose there appeal if they aren't balanced with a healthy social life. They are akin to drugs, they will have diminishing returns over time, the internet is the drug of choice for the lonely but it's just that, a drug, a dopamine hit to fill a void.
I've been TRULY alone for over a decade now, battling diseases that just get worse despite monumental efforts. I could cope with the loneliness, with hope in the beginning, now all my fond memories are a decade+ in the past and replaced with a life of horror. I can't really enjoy anything and if I do it's only momentary. I wake up in a depressed state and go to bed in one without fail, anything positive is fleeting.
Listening to music in the dark and daydreaming with my eyes out of focus about my past or dreaming of a future that will never be is the closest thing I have to feeling 'whole'. It's similar to using drugs, I go to a comatose state with the help of music, darkness and pain built up for decades.
Nothing works, I am an introvert but I am not a true loner, i've been cast aside like a leper without a colony. I'm not meant to live like this, the loneliness is fucking horrible, the pain only grows with time. I used to think, i'd be able to handle loneliness, I was fucking wrong, I didn't realize how much I used to have.