I'm not a man, @Rocaille, and I do subscribe to something similar. i'm polyamorous, have a couple of consistent partners and (in a time outside of a global health pandemic) freely engage in casual sex. There are, of course, some potential health risks attached to this, but my experience of the poly community is that everyone is very rigorous about testing and are open about discussing when they were last tested, previous partners, etc etc. I'm not blase about it, but equally i'm not going to be terrified about something that has a relatively small risk. I have thought about getting an HPV vaccine though, if i ever feel confident enough to date again.
I think I entirely have the luxury to be 'frivolous'. I don't have children, I have access to birth control and I have partners who i trust to be sensible - we use condoms, we get tested, and no one has unprotected sex (or if they do, they tell each other and let the other person decide what they want to do about that).
Regarding the point made above, asking @noego if he'd really be happy if someone 'called it a day and started something up with someone else'. Well, a few things on that point. Not speaking for @noego here, but for me, relationships (romantic or otherwise) are not about ownership. I do sometimes wonder if people get married just to tie someone to them, out of fear of being left. And yet, marriages do end - people do 'call it a day' and start something with someone else. I think the thing I like about polyamory, particularly more modern, unhierarchical approaches, is that there is acceptance about the way that relationships can morph and change. One of my partners has a very close, platonic relationship with his ex-wife, who he freely admits he will always love immensely. Their relationship changed, and it wasn't easy, but they worked it through and it's been able to shift into something else, which is still important in their lives. My other partner and I started out as something much more casual and less emotionally invested than we have now - we were good friends, who started sleeping together, and it grew into something else. it's not easy to label, and neither of us are that bothered about labelling it. It works for us - it's a close, intimate friendship, and we love each other in our own way. Perhaps one day, we'll stop sleeping together and go back to just being close friends.
I think we have a lot of expectations on the way that relationships 'should' look. And some people want the whole marriage, babies, my-partner-is-my-best-friend idyll. But I think too many people don't enter into traditional monogamy 'consciously' - in the sense that they don't really examine their choices or why they're doing it, or even if they really want it, but just because they've never taken the time to think their could be an alternative.
Anyway...just some thoughts from me, in a bit of a ramble.