"What a lovely surprise to finally discover how unlonely being alone can be." Douglas Coupland
what is unlonly
Although not grammatically perfect, the difficulty being the "concept" of a person or place being "unlonely" (compared with, say, "unlovely"), the deliberate use here is poetical and metaphysical. In this context "unlonely" should be acceptable.
Ya, 'unlovely,' is correct. 'Unlonely' is not correct even looked it up on wordperfect. So it's NOT acceptable.
Ha ha, "unlonely is a dreadful adjective". I don't think Americans use dreadful as much as English people.