I went to a party a few nights ago and, to my alarm, one of the first things I saw upon entering the hotel suite was a 65-year-old man entering a 25-year-old woman against a wall (and trust me, she was not his partner).

That this ''gentleman'' was entering her was surprising, but the fact that there were no condoms in sight was really concerning. Especially because I saw this same ''gentleman'' repeat the exercise with another 20-something ''guest'' 20 minutes later.

Read more from James St James: Are you facing a relationship breakup?

Setting aside questions about the appropriateness of this man’s actions and what appeared to be his considerable stamina, I was stunned that in 2018, a mature, educated, well-informed and supposedly intelligent man was having unprotected sex with not just one, but two women he didn't really know.

And it seems he is no orphan.

Family Planning New South Wales recently surveyed 2339 men who used online dating services and found that 77.5 percent had unprotected casual sex in the previous 12 months. Even worse, it found that men over the age of 60 were much more likely to have unprotected sex than their younger counterparts.

Very disturbing was their finding that 49 percent of men over 60 did not know that Australia’s most preventable sexually transmitted infection, chlamydia, often showed no symptoms. In other words, these men did not know if they had this STI -- and no idea if they were passing it on to others.

It was evident from the survey that older men, and therefore older Australians, were more at risk of STIs than younger Australians. It was further evident that this effect was being exacerbated by the divorce rate more than doubling -- from 13 percent in 1990 to 28 percent by 2011 -- and continuing to grow in the past seven years. There are more older, newly single men looking for sex and pursuing it without the appropriate protection for themselves and their partners.

The fact that in 2018, we have the medications needed to prevent HIV becoming full-blown AIDS is no justification for unprotected sex with casual partners. HIV and AIDS are not the only STIs, but like all of them, STIs have a devastating and expensive effect on the lives of those infected.

So why are so many older men being so stupid? 

The survey examined this phenomenon, finding that common excuses among older men included: believing their partner did not have an STI (75%); monogamous relationship (45%); not wanting to (34%); their partner not wanting to (15%); and safe-sex not seeming important (14%).

I'm not sure that any of these reasons can be adequately applied to the gentleman at the party I referred to earlier. With the exception of a monogamous relationship, none of these reasons make much sense. And given that the survey respondents were finding their partners online, I suspect that a monogamous relationship was difficult to substantiate.

The reasons younger men were not using condoms were also examined. It was found that 65 percent believed their partner did not have an STI; 51 percent thought their partner was using contraception; 50 percent said they did not want to; 36 percent said the relationship was monogamous; and 32 percent said they could not help themselves.

I suspect that the last of these reasons was, in truth, more common that any of the others, with respondents unwilling to admit that they had behaved irresponsibly -- in a way that is dangerous for them and their partners.

Research suggests that the average Australian woman has eight sexual partners in her life, with the average Australian man having 11. Further to this, 58 percent of men and 56 percent of women report having more than one sexual partner.

I have no objection to casual sex and have had many more that 11 sexual partners, but I have a real objection to contracting an STI, and fail to understand why many more (if not all) Australian men do not feel the same way.

I am left wondering if any of these people saw the savage AIDS television campaigns of the 1980s. Do any of them remember the number of people who died from AIDS in the 1980s, '90s and early 2000s?

Do they understand that condoms do a great deal more than prevent pregnancy? Do they recall the safe-sex messages taught at school, which only the very oldest of them would not have heard? 

Or, like smokers who don't think they'll get lung cancer, alcoholics with liver disease and drunk drivers who don't think they'll get caught, do they simply think it won't happen to them?

If they think this, it is anything but a safe bet. There are in the vicinity of 500,000 cases of chlamydia alone diagnosed in Australia each year.