Many men try to make fucking without a condom safe from HIV transmission by trying to find a sex partner of the same HIV status.
In theory, if two HIV-negative guys fuck without condoms then there is zero risk of transmitting or contracting HIV. However in a recent study, 1 in 10 men incorrectly assumed that they were HIV-negative when they were in fact HIV-positive.
Asking or guessing someone’s status is not a reliable way to reduce or eliminate the risk of getting or passing on HIV during condomless sex.
He could be either. Some HIV-negative men think a sex partner is probably also HIV-negative because they would have offered to use a condom if they were HIV-positive (especially if they're going to be the top or insertive partner), but he could be HIV-positive and think that you must be HIV-positive too, because otherwise you'd want to protect yourself from HIV and use condoms.
If you've been fucking with other partners without using condoms then it's possible that you're HIV-positive and not know it, and therefore you could be the one passing the virus onto new sexual partners.
However it should be mentioned that none of these provide protection against other STIs. Using condoms and water based lube remains the most reliable method for preventing STI transmission during sex and even then it is still important to have regular sexual health check-ups.
An option that is available to people who are HIV-negative in terms of preventing HIV transmission is a process called ‘Talk, Test, Test, Trust'. This process is only suitable with a long-term partner as it takes three months to complete. ‘Talk, Test, Test, Trust' requires both partners to get an HIV test together, to continue using condoms with each other and other partners too if that is agreed upon, for a period of three months and to then get tested together again after that three month period. Only after the second test-results have returned negative can both partners reliably know they are HIV-negative and thus can have condomless sex without any HIV risk being involved. However, this process also requires a high-level of trust and communication between the partners for it to work. Furthermore for this process to be reliable several considerations and conversations need to take place, so to find out more about the ‘Talk, Test, Test, Trust' option check out http://stayingnegative.net.au/hot-topics/relationships