I'm sure there are others, but the only time I can remember posh going up, without Seymour's involvement is, when Robert takes her out for a drink in chapter 2. I can think of three times Ian's chad variable can go up, without the need for sex involved. Put it down to my bad memory I guess.
Running a quick search, Lena posh changes:
Ch.2:
when on date with Robert, "It's really nice" +1, "Not my style" -1
Ch.3:
when meeting Charles: "Run away" +1
when talking about passions with Holly: "making money" sets posh to 2
when preparing for meeting with Seymour: "change clothes" +1, "wear casual clothes" -1
Ch.5:
after entering the club: "i like the music" +1, "not my style" -1
Ch.6:
when deciding how to spend free time: "get ready for Seymour" +1, capped at 3
Ch.7
selling the necklace: -1, keeping the necklace: +1
when getting ready for girls' night out: picking basic dress or athletic outfit -1, wearing other outfits +1, capped at 2 or at 3 for charisma dress
Ch.10
when visiting the boutique while shopping for clothes: +1 if at 0
when buying the expensive dress: +1
Ch.11
when visiting the cultural center: "kick the dog" MAX POSH
when asked about travels by Seymour: "love it" +1, "it's alright" -1
when speaking with Emma about shopping: "love it" or "yes" +1 capped at 5 and 4 respectively, "not really" -1
when asked by Emma about dressing feminine: "definitely" +1, capped at 4
Ch.13
when asked to return necklace: "i thought it's a gift" +1
when deciding about free time in Rome: "go shopping" or "go back to hotel" +1
during date with Stan: "romantic comedy" or "french arthouse" +1, "horror movie" -1