This thread ties in very well with other threads out here.
1) Regardless of what you do and how often, your risk only goes DOWN if you are tested regularly. Whatever your 'STI-avoidance-system' is as a guy, just get tested as well. And for married guys who are just ignoring it because a positive result would end your marriage: your only chance to survive is to hear the news first.
2) Math time: Men, think how much the average woman needs to make in Ottawa to live. Then divide that by what you spend on an average date. While not a perfect indicator, it gives you an idea of 'her number'. If that number makes you uncomfortable, then the way to fix that is to PAY MORE. Half the comments on here are 'how is $$$ considered reasonable now', 'used to see her before her rates went up', 'good value for money'. You can't have it both ways.
So that's basically it: If you want to keep both you and her safer, get tested; and if you want her to go on less dates with other people, pay her more.