i always feel this way... i get this embarrassing sense of hope irl or online that somebody is taking a liking to me and i build up the idea in my head, until i find them in another situation and they choose to talk to someone else instead, and they will give that pitiful smile towards me or the insignificant small talk. it makes you wonder what you were to that person at the point when you thought they had taken a liking to you.
i think with all the people in this world though it's ridiculous to believe there is no one you'll find a true connection with. i've met people who have felt they deserve no love because they have always been knocked down by being used by people or just being their last choice, but I've found myself in so much admiration of these people, that they could hate themselves so much despite so many amazing things about them.
disappointment and rejection hurts, a lot, but you will certainly find someone who will choose you as their first choice, if you search for the right person in the right place. it'll take time.