I am in so much pain

my girlfriend and i have s3x three times a month. im a man in my early 20s and i have a very high drive. i think she's the prettiest girl in the world and im not just saying that because we're dating. ill never be able to put into words how addicting she looks. its been almost 2 weeks and she's been shutting me down when i bring up s3x. I feel so ugly. Ive never felt this kind of dejection about my body or my looks. Im struggling.