Is AUTHOR wrong in the post ? POST : Repost since my original was too long. Catchy title, eh?

So the shortened story:

At 31, I financed my first car (before that I had a jeep that I bought in the early 2000's for cash.) Having never financed a car, I failed to find out if they added the cost of sales tax and registration and whatnot to my financing cost. They did not, unsure if the fact that i bought it in a neighboring state has anything to do with it. 

So when the registration comes to the local title office I am hit with an unexpected $515.16 fee. As I am busy restructuring my budget, I don't have an extra $500 on hand.

I tell my girlfriend about it, not overly worried because my tax return should hopefully show up before my temporary plates expire. My girlfriend offered to loan me $500 out of her travel account (money we set aside so she can come with me on work trips. Work pays for me not her) and I can just pay it back with my tax refund. I agree that it's a solid plan. 

Fast forward to last night, dinner with friends. One of our friends has brought a date none of know him. I ask my gf if she wants a drink, and she jokingly says yes since I owe her $500. I'm getting us drinks and she fills in new guy about why I owe her money (for clarification, she's not bothered by the loan). When I get back I get to listen to a tirade about how people who borrow money from their loved ones are assholes and deadbeats. Dinner is ruined and the subject is changed after he leaves. 

Reddit, am I the asshole, just none of my friends want to say it?