No, they are no longer together. They actually called it quits before the birth of their daughter. They remain close but are currently dating other people.
If you're asking how it detects pregnancy, it does so by having a chemical dye that reacts with the hormones that are present when pregnant. If you're asking how it gives a negative result and then...
Depends on where you are at in your menstrual cycle and if he actually got semen into your vaginal tract far enough. I would advise a pregnancy test.
Answer .
WELL DEPENDING ON YOUR CYCLE YOU CAN...