When I say she tended to cheat on her partners, what I mean is that she cheated on every boyfriend she'd ever had up to the point I lost touch with her, without exception. I asked her about it one rainy evening, and she said she didn't set out to cheat; when it happened, it was accidental.
That's an idea I've heard echoed countless times in countless conversations when I talk to people who've been unfaithful. "It was an accident. I didn't mean to do it."
There's a certain element of self-serving justification in there somewhere. It's likely related to the fact that folks in openly nonmonogamous relationships are at lower risk of sexually transmitted infection than folks in nominally "monogamous" relationships who cheat. If something is an accident, we're not responsible for it. If we remember to bring condoms, or talk about sexual history, or do any of those other things, we're obviously planning for it, and therefore it isn't an accident. If it's not an accident, we are responsible for it.
It's a thin justification, to be sure, but it's remarkably resilient. And part of that, I think, is we don't acknowledge the difference between accidental and unintentional.
If I make a choice to do something (and as long as we're talking about consensual sex, if I'm in bed with someone, it was a choice), then the thing I'm doing wasn't an accident even if I didn't intend to do it when I got up in the morning. That's a distinction that matters. I might not have intended, at first, to cheat on a partner, in the sense I might not have woke up and said to myself "you know, I think I'll betray the confidence of my lover this afternoon! Maybe I can pencil that in before I go to the gym"...but it was still no accident.
I realize that people will attempt to rationalize their choices however they can, and conflating "accidental" with "unintended" is a way to do that. Yet, maybe, just maybe, if we stopped seeing "it was an accident!" as a validation, if we as a society didn't accept the notion that cheating is less wrong if it is less planned, things might change. I'm not naive enough to believe people might stop cheating, but maybe they might at least be a bit more safe about it.
I'm writing one blog post for every contribution to our crowdfunding we receive between now and the end of the campaign. Help support indie publishing! We're publishing five new books on polyamory in 2015.