I read 'intimate friends' as a metaphor for homosexuality; or at least what is now known as. Although buggery in itself was a capital offense, AFAIA before the later part of the century there was no prescribed behavioural or other stereotype for a gay person. Victorian men were all just a bunch of straight dudes.

src wikipedia:

'Foucault cites "Westphal's famous article of 1870 on 'contrary sexual sensations'" as the "date of birth" of the categorization of the homosexual'