Even before AIDS, most gay men longed for that one guy to whom they could commit their life, that one special man with whom they could settle down in a permanent, faithful relationship. But we know what happens most of the time. But with each new relationship comes a new set of exposures. True, there is a much greater motivation to settle down with one person now, but the difficulties in finding that person haven't decreased. There seems to be an inverse relationship between the amount of sexual interest, arousal, and excitement, and our ability to use sound judgment.
Men have a terrible propensity to do stupid and careless things in the heat of passion.
Perhaps, you went out not intending to connect, but you met somebody new and got carried away. Perhaps, you and your partner agreed to abstain from certain kinds of sex, or agreed to use a condom, but in the heat of it all, you threw caution and rational behavior to the wind. Sex is often accompanied by drinking or drugs. Take the risks just described and multiply them many times over if you've been drinking. In that setting, the best intentions become almost worthless.