It won't bring comfort or pain. It won't bring anything except nothing. Getting there will probably be painful and scary; that's how it is for most people when they die. Your present will no longer exist because you were hoping for a future that one can never experience.
From then on, you'll only exist in the past of countless others who wish you could've stayed longer. They might wish for things you never would've willingly delivered, or miss you for things about you that weren't true. They will miss you for a future unrealized, looking ever forward like you once did. However, the greatest sadness will be the moments when they wished you were there.
..............
Needless to say, not having a girlfriend is a bad reason to not want to live. I doubt it's even your real reason. The most common reason for hating existence is hating yourself. If that's the case, you won't get better until you love you.
I've met several people who couldn't improve, no matter what they tried. I was stuck in that place for most of my life; cursing that I was born; unable to live for myself. This was all because I was the only person I truly hated. Eventually, I found that my inability to be happy was because I never loved myself. Loving myself wasn't sufficient for happiness, but it was necessary.
It was often the thing other people in the same spot needed as well. They had often obtained most of what they needed already, but that one piece was still missing. Don't need a gf to love you if you have a self that loves you 😁