i feel the same, but if im not around people i like or care about, its just tiring and it makes me more sad eventually. talking on the internet is always better imo even just friends i get tired after too long, unless it's my s/o i guess. but i have read that a contentedness comes from having meaningful relationships with others, and helping your friends must have a lot of meaning to you
you know when you're feeling down it's usually because you feel alone, either like there's some problem with you alone or just because you're alone
but when you're feeling down with other people, you can't feel quite as down because you're not alone so a lot of the reason you're down fades away and you're just a little less down
when my friends are sad it usually distracts me from being sad about myself because i start thinking about making them happy instead of feeling bad about myself so in a way sadness can be used to create happiness or at least contentedness