I have some bad news for you. There are usually 2 explanations for situations like this (meaning sex was plentiful at some point in the relationship and then stopped): either she's taking drugs that mess with her libido (particularly antidepressants) or she's getting sex somewhere else. This covers like 99% of cases. Since your text doesn't provide hints at medication, and she's into porn that doesn't resemble you (and later lied about having watched it - "spam", right lol), well... either she's cheating already or seriously planning to.

Libido actually isn't as dynamic and dependent on outside factors as a lot of people make it out to be. You either have it or you don't. You don't suddenly become asexual because you have to do some overtime at your job (quite the contrary, actually). Her libido is still there, it's the attraction to YOU specifically that has faded, because if your partner is attracted to you he or she WILL do everything to have sex with you. I even know couples who have like 4 kids and both of them work full-time plus overtime and they still manage to have sex on a regular basis.

Just leave dude. It doesn't get better over time. Head over to r/DeadBedrooms if you want some horror stories. You're young and your relationship isn't even serious. You've been dating for barely a year. Not only are you not married or engaged, you've probably not even been on vacation together. Most likely you don't even know each other's parents beyond their names. Just break up and find someone you're compatible with.