Okay, the good news is that she's not threatening to leave you because of your performance, it's because she is worried that you are not attracted to her. Women's egos are a very fragile thing, even most 9s and 10s if you dig deep enough. She (as you said) now has a compèlex about you not being aroused by her.

Mediterranean girls and women have the same desires and insitincts as all women, however (I live in Italy), they are famous for their drama, temper tantrums and hysterical behaviour and this is not unwarranted to a certain extent (all women are capable of it, but it does tend to be a little more extreme out here).

With regards the erection, I think there's enough advice and suggestions above to keep you going.

With regards the Spanish HB, I think communication is the way foreward. In order to save this, and also to reassure her, she needs to know that nyou are physically attracted to her. So just speak very openly, tell her that you haven't had much practise fucking in public and in unique places and it's something a little new to you. Better that than lose her