Spotting 3 days after ovulation?

Unless she's been charting her temperature over the course of 3 or 4 months, your girlfriend can't possibly know if she's ovulating. She can't put her trust in some sort of 'app' or 'period tracker' she might be using.

"Maybe ovulation bleeding"??  Women don't bleed when they ovulate. Most women don't even know when they ovulate. 

Assuming she ovulated on Dec. 7 and assuming she conceived on that date, she wouldn't experience ovulation bleeding on Dec. 10 - it would be too early. Implantation bleeding is very rare and, when it does happen, it doesn't occur until at least 10 days after conception, when the fertilized egg implants into the lining of the uterus and establishes a pregnancy.

In spite of all the horror stories you might have heard or read, don't waste your time worrying about "precum" - it's highly over-rated as causing pregnancy. "Precum" is   nothing more than a male's lubrication fluid, and 97% of the time it doesn't contain sperm cells.  

Spotting is normal and common at any point in a woman's cycle.  Pregnancy is the LEAST common cause.  And it can't be implantation three days after ovulation anyway (assuming she calculated ovulation correctly).  It would be much too early for that. 

I have no idea what started the myth that implantation bleeding is rare, much less so rare as to be called "impossible, really."  It happens in an estimated 20% of women, some estimates even have it as high as 1/3 of women.  That isn't remotely medically rare.  Certainly not impossible.

No woman ever truly experiences spotting during implantation. It's as rare as finding out you're pregnant 1 week after conception. Impossible, really.

What is the color of your gf pubes?

You'll definitely know in nine months.

If she did conceive and was going to have implantation bleeding it wont be until around 14 days after unprotected sex so stop stressing.

And the boyfriend knows all the details. Yeah right.