Not sure you will follow me on this but please just consider:
=> if you play the game carefully, Ian does not ask Lena to explain what happened with Cherry and in that case, there was officially NO threesome with Cherry and Axel.
=> If you deny Ivy, nothing happened between them apart from training to kiss (innocent enough) and if you turn down the cigarette on chapter 11 epilogue, Ivy expands on how Lena was the nerdest of nerds in her youth.
GRANTED:
- if you fool around with Ivy, then yes they did things in her youth + if Ian offers to listen, Lena had a threesome with Axel and Cherry + if you accept the fag, you were a naughty teenager.
=> I come back to my initial post:
Read the thoughts and dialogs of Lena in the first chapters carefully: is this the kind of girl that did crazy stuff in high school ? Is this the kind of girl that fools around easily ? Is this the kind of girl that accepts threesomes from her boyfriend easily ?
Sorry but No. That slut side from Lena comes from nowhere if she fucks Robert. Goodness gracious, even the line, when she invites Robert for drinks sounds wrong compared to anything we have read before about her.