Loneliness is not always pushed aside by the presence of others.
You can be a kid at home with your sulky, troubled parents and feel excruciatingly lonely. Or, with friends at a dinner and suddenly you feel the ache. Piercing.
To me, all three in this photo (young woman, sitting alone, and father and daughter at the bar), encountered on my way to the shop, appear lonely. I could be projecting, but this was my impression.
On the other hand, it is also true that loneliness can be puffed down by non-people things. Flowers, for example. Anything else? No, can’t think of anything else.