I use condoms with new partners and will continue to do so. Even if they are sti free, there's nothing stopping them from having unprotected sex with a new partner who may not be sti free. When the relationship becomes more and I want to stop using condoms I'll ask for them to be tested and will request to see the results. I currently am tested every 6 months but am thinking I might go every 3.
In my youth I never used protection from sti's and am very very grateful that I was lucky (I slept with quite a lot of boys). After marrying dh 18 years ago I only had tests done when getting pregnant. A year ago we opened our marriage and I've used condoms but dh had not with his gf from last winter. Neither of them would go get tested so I did.
I'd rather be safe than sorry years later from not being proactive for my own health.