So what we have is a group of adults with past lives, loves and traumas and definite ideas of their own. You can agree with them or not, influence them or not, even completely turn their lives upside down - player choice. Not all the companions have previous sexual trauma, Halsin doesn't, Gale doesn't, Wyll doesn't, I don't get the impression that Minthara does and certainly not Lae'zel or Karlach. That they aren't innocent young adults doesn't mean they have sexual hangups. One comes from a completely different culture where family units don't even exist.
To be fair, Halsin was kept as a sex slave for 3 years when he was young, I'd say that qualifies as sexual trauma. And Gale's relationship with Mystra may not fall under trauma, but it clearly wasn't a healthy relationship where both parts were equal.
