According to US Magazine:
" 'He didn't use a condom,' says Grubbs, who adds that Woods also didn't ask if she was on birth control, either. 'It wasn't even discussed. He just never used one.' Apparently, he also didn't use condoms while bedding 33-year-old restaurant manager Mindy Lawton, according to Lawton's sister, Lynn. 'She said he never wore condoms,' Lynn told British tabloid, News of the World. 'I was so worried she might catch a disease, especially as we suspected he was promiscuous.' "
I'm guessing Elin didn't know about this when she left, taking a crappy pre-nup and vaginal warts with her. You know, $80 million doesn't buy happiness, but it would buy a lifetime's supply of Valtrex... your fault.