@Hooper - you anticipated this!!!
With the greatest respect, the frequency of sex at the start of this relationship is immaterial. It is not a consideration right now. In the future when sex is no longer re-traumatising and has become an enjoyable experience? Sure. Have the conversation then.
But the implication that a woman with ptsd from sexual trauma, who is being retraumatised by sex, should be putting her partner's libido before her own recovery? Wtf???
If this was someone recovering from cancer, and sex was making their cancer worse, would you suggest that "Cancer aside, consider my sex drive..."
If libido is such an insatiable requirement for this guy that he literally can't get by without it, even knowing that it's retraumatising his partner each time, then he needs counselling and/or a new relationship.
Women never (ever) have to grit their teeth and bare it if their partner wants sex and they don't. And when the sex is actually doing the woman an immense amount of damage, and the partner KNOWS it, the fact that he'd put that on her and not accept it as his own personal issue is not only disgusting, it's criminal.
It's very common to need to re-learn intimacy after sexual trauma. It's very common for sexual abuse victims to need "no sex" for a period while they recover.
No means no. Pressuring a woman into sex regardless of "No" is rape, regardless of what his "libido" would prefer.