Whitman uses “dear friend” and “lover” more or less as synonyms and the entire American reading public apparently found this a completely normal description of affectionate male friendship until about 1890, at which point people began occasionally to have Concerns.

"Friend" and "friendship" are used with specifically romantic, queer connotations as late as 1920, cf. this journal which I found because Dorothy L. Sayers of all people contributed to it.