As you have said, it is difficult to make such decisions when in love/thoughts are mush, or something like that... your partner's thoughts and decisions are equally as effected. Can she make a rational decision, yes, but she can also make a regretable mistake. Perhaps use your best restraint until she has been able to fully absorb the information/situation.
To the CDN guy... sounds like most of your partners, hypothetical or what not, had low self esteem or were mildly depressed. If someone ever tells me they want to have unprotected sex with poz person - that will be a red flag to slow down the relationship and take time to educate each other fully on the risks. So that they do not regret it in the future and turn things around on you. You may someday, meet the person who legally challenges you to the fullest extent of the law and it's loopholes.
Being positive is the beginning of a lifetime of change.