Yeah that's a good point - it's frustrating when people sexualise everything. Perhaps it's a symptom of their own sexual repression, which they project onto other people. After all, if they are thinking about sex all the time, they assume other people are too! I do also think our culture has retained some Freudian ideas even if they are not scientifically valid... the idea that nearly everything people do is motivated by sex.
You make a great point about child abuse and sexual shame. Shame about sexuality is one of the primary tools that religion uses to keep people coming back, as most people experience sexual fantasies and thoughts fairly frequently, thus they feel guilty on a regular basis and have to repent continually. You might find this book interesting if you want to explore this topic further: Sex and God: How Religion Distorts Sexuality
But yeah I'm in a partnership with a woman now and sometimes it's frustrating feeling like our relationship gets sexualised. I feel like my relationship with her is primarily based on a foundation of friendship, first and foremost. We have gone long periods without sex for health reasons, so sex to us is really just a nice bonus - but not a necessity. However, people act like it's the only reason we're together.
I recommend that you read a book called Sex and God: How Religion Distorts Sexuality by Darrel Ray. It can help you come to grips with your background and find a different (healthier) outlook on your sexuality. It could be a life changer for you. Best wishes.
There is a great book about exactly this. Highly recommended.
Sex and God: How Religion Distorts Sexuality
https://www.amazon.com/Sex-God-Religion-Distorts-Sexuality-ebook/dp/B0073WNSV6
Darrel Ray - Sex and God: How Religion Distorts Sexuality https://www.amazon.com/gp/product/B0073WNSV6/ref=dp-kindle-redirect?ie=UTF8&btkr=1
If your girlfriend was brought up in a religious atmosphere you may want to read Darrel Ray - Sex and God: How Religion Distorts Sexuality https://www.amazon.com/gp/product/B0073WNSV6/ref=dp-kindle-redirect?ie=UTF8&btkr=1
Not sure that this will help immediately, but it may give you some insight into what you've been through: https://www.amazon.com/dp/B0073WNSV6/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1
He has a great podcast also.
Darrel Ray - Sex and God: How Religion Distorts Sexuality
https://www.amazon.com/gp/product/B0073WNSV6/ref=dp-kindle-redirect?ie=UTF8&btkr=1
Get this book to help you understand:
https://www.amazon.com/dp/B0073WNSV6/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1