The one trait that separates man from other animals is the ability to make decisions that override and control animal instinct and sexual procreation is not the most basic human instinct, survival is way ahead of sexual gratification.
The HIV virus is not transmitted in saliva or tears and can only be transmitted via semen, vaginal fluids, blood, and breast milk. HIV is transmitted by the exchange of contaminated fluids, which includes IV drug users, so knowing the sexual history of your partner is immaterial if your partner is also an IV drug user who shares a contaminated needle. However, I was not referring to HIV. Gonorrhea, syphilis, chlamydia, herpes simplex, and a long list of other STD's have become resistant to antibiotics and/or are not curable. Herpes can be transmitted by contact with infected genital fluids and in urine and is incurable. Also the proper use of a condom is a rather complicated process. The CDC recommendation for the proper use of a condom is a 15 step process that few men, women, and teens take the time to observe if they even think about using one; and condoms do break.