Zelophobia, what you suggested seems rather pessimistic from my point of view - in that case we would have to wait about at least 5-10 years to have completely normal relationship. Way too much. Although me neither could find a solution, which is why I asked for ideas.
But in that case, do you suggest that people in late teens and early 20s do not have sex at all or very rarely unless they are adventurists who like having sex in the car? I really hoped there was something I was missing to see.
As for the other answers - car idea is great for me, but not to her, she likes absolute privacy for that and I completely understand.
And my home is rarely empty, because my parents don't really have working hours, and only leave home for a couple of hours a day. Even it is empty for an hour or two, my girlfriend lives on the opposite side of the town, it takes her at least an hour to come to me
Any other ideas? Please?