As the New York Times, the San Francisco Chronicle, and numerous other sources have noted, self-reported unprotected anal intercourse among gay men has been on the increase over the past several years. This increase seems to be cutting across all demographic groups, although probably for different reasons:
a. Some older gay men - i.e., those of us who were out when AIDS first landed on the scene 20 years ago - seem to be succumbing to a kind of fatigue. No one (but no one) predicted 20 years ago, or even 15 years ago, that we’d still be grappling with this disease now. The assumption was that by this point either we’d have cured it or, more likely, come up with an effective vaccine. (I was sixteen in the spring of 1985, when then-HHS Secretary Margaret Heckler officially announced the discovery of the HIV virus and the availability of a test for it. She predicted that within two years there would be a vaccine - a predication that even my 16-year-old brain suspected was far-fetched, based on what researchers already knew about HIV’s capacity for mutation.) The cumulative effect of a couple of decades of fear has, in some men, produced active relief when they test positive, for the simple reason that they no longer have to worry about seroconverting - it’s already happened.
Public health officials indulged in an orgy of self-congratulation in the later 1980s, when the rate of new exposures plummeted among gay men. It's increasingly clear that that outcome, welcome as it may have been, resulted less from any well-advertised "message" and more from men watching their friends die. Thanks to combination therapies, a lot fewer men are having that experience. Indeed, although I've been out since late 1983, I have yet to lose anyone even among my more distant acquaintances.
b. African-American gay men have always had a disproportionately high rate of infection, and among younger black gay men the rate in some locations is simply astronomical. Black gay men are often caught in a terrible psychological bind: the gay male community is perceived as overwhelmingly white and affluent, partly because it’s white, affluent men who are most able to structure their lives to make being out possible. Financial independence means that an affluent guy can afford - literally - to alienate his family for a while and wait for them to come around. For poorer people, that’s a step that can be far too costly. The gay community also has its own rather ugly history of racial stereotyping (depicting black men as mindless Sexual Studs), and, in the 70s and early 80s, explicit discrimination in some bars and clubs.
In addition, the African American community on the whole (speaking in broad, general terms and acknowledging lots of exceptions) is pretty intensely religious, with widespread condemnation of homosexuality in general and gay men in particular. In some cases, homosexuality is seen as a betrayal, or (perhaps worse) as a "white thing." Black gay men have reported (both in surveys and, anecdotally, to me personally) that tolerance is certainly possible, but it's usually conditioned on not advertising your difference. Consequently, lots of black men will have sex with men "on the down low," meaning affairs with men while maintaining a public facade of a girlfriend or wife. There's some indication that for many of these men the act of using a condom requires an (impossible) acknowledgment of their sexuality. Of course, these men are equally unlikely to use condoms with their wives or girlfriends, resulting in an additional round of potential transmission.
c. Pharmaceuticals manufacturers have tended to exaggerate the efficacy of HIV therapies by depicting almost pornographically well-muscled men “moving on with their lives.” No mention of the diarrhea that may take an hour every morning to overcome, or the lipodystrophy that results in sunken cheeks and the infamous fatty-tissue “crix hump” growing on the shoulders(names for Crixivan, a new-generation drug that is perhaps the greatest offender in its young-studs-mountain-climbing advertisements), or debilitating anemia, or the simple possibility that the drugs won’t work in a given individual - as happens, eventually, for many.
d. Young people are young people - without the reminders of death, they will tend to assume that it can’t happen to them. Nothing is new about that.
e. People want to fall in love, and falling in love means falling to the moment and not worrying. It’s denial of the most human kind.
f. Drug and alcohol abuse are major contributors. One of the unfortunate inheritances gay men have is a tradition of bars and dance clubs as our primary social spaces - a relic of a time when they were our only social spaces. Of course that means additional opportunity for alcohol problems and, as has become more prominent lately, for use of party drugs like crystal meth, ketamine, GHB and ecstasy. The first three in particular can completely cloud judgment.