Mine happen quite suddenly. We doing heavy petting for a long time > one year. We didn't have penetrative sex because she scared pain. The most that we do is to get naked and I rub my brother against her sister. Good for us and she can O.
But I always try and she always stopped me.... I guess I am a bad boy... hee hee.

Then one day she was really wet and I try to have sex and this time she didn't stop me at all. I went in and she was also very aroused....she keep saying "fuck me" "fuck me", "it is really good". I am damn encouraged and keep pumping... and then when I came I said "shit" and she pushed me out and I sprayed it all over her

We didn't use condy at all because it is unplanned. after that so worried and buy the test kits and was very tensed.... We tell ourselves that we wouldn't do it again but I guess it is like opening the floodgates. From then on we have sex regularly.