Someone's negative test result is valid only up until the first time thereafter that person has high-risk sex. Disclosure and discussion are important (and disclosure by poz guys is legally required in many places), but basing behavior on what someone merely tells you is foolish. Every day in the U.S. alone, thousands of gay men contract HIV by having condomless sex, many of them with men who thought they were negative. This is why it's so important to take the responsibility of protecting yourself, regardless of what someone tells you.
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