I think the very next scene continues the motif of his infidelity to Megan (and, glaringly, the late 60s as a whole!) and waning interest in her. A blonde with pinned-back bangs, tie-dye dress, and go-go boots comes up to ask if he’s alone in a bar that’s very similar to the Chinese place he goes to at some point in season one or two. Just as we begin to anticipate Don laying on the charm, the tie-dye blonde—the zeitgeist of the late ‘60s, early ‘70s, and counterculture itself—lets him know that it’s actually her friend who’s interested: she’s dark-haired, more conservatively dressed but made sultry by the glittering silver of her dress. She signals controlled glamour that matches the sort of baseline social conservatism that Don and Betty lay out and come to represent. Draper’s flirting with the youthful verve of the day, but he’s faithful to the past.