I have this girl who showed interest in me and I was thinking about how much it can cost to me.

Well in Italy she lives at around 40kms from my house:

If I take her to my house and take her back home : 40kms x 4 = 160km It's like 20 euros of fuel

Then we've got the highway payment which is 2.50 euros x 4 =10 euros

At least 30 euros just to see her... Restaurant, some gifts, flowers, exc... Do that 3 times a week and I can see why I stayed alone for 25 years