Rahx, no matter what the Bore always says, a big fat juicy cock is not the be all and end all of fucking everything. Yes, it's nice and everyone here worships cock but sometimes you have to focus on the smaller things in life. Forget that thing for a while, hang out and have fun with your girl, learn something new about her, bake her a cake, make her a mixtape or draw a funny picture for her, fucking take it back to a more innocent stage. When things get cute and flirty, don't feel pressure to perform but instead just focus on her, just holding and kissing her, maybe eventually let the cock back into play but as long as you're fixated on your dingdong it is staying in your pants. No one is to go near it, not even you.
If you can get Cialis then maybe try that as fallback but don't rush straight to meds. Give your peen a break and stop being so hard on it or it won't be hard. That little feller feels the pressure way harder than you do now. Yes, everyone loves cock but sometimes you need to let go of the things you love so that when you get back to it you appreciate it in a whole new way. And so will she, after a while of not being allowed near it she'll be all over that shit. And no, she won't go looking for stray dick the moment she can't get yours, unless she's a legit sex addict nympho.
Tldr; forget the dick for now and focus on having fun. Fun with the dick will follow.