Hello HeyItsKiki93,
Did your primary know that sex is something that could happen between you and your secondary? If your primary knew that, then I would not call what you did cheating. My understanding is that cheating is when someone has sex with someone else without first getting their other partner's consent. And I'm saying that if you had your primary's consent to have sex with your secondary, then it was not cheating. Now it may be a breach of your rules and agreements, but that's a milder infraction than cheating. That's my take anyway. And I'm not sure how clear you and your primary were with each other before this incident about what the rules would be. Far from being cheating, this whole thing could be a mere misunderstanding.
You're saying your primary wanted you to check beforehand. Does this mean he wanted you to check with him before the first time you had sex with your secondary, or before every time you had sex with your secondary? Did he state that clearly? Did you clearly understand him? Did you agree to adhere to that rule? If you promised him that you would check with him every time you and your secondary were going to have sex, and then you didn't, even if it was only one time, you still failed to keep your word and in that case yeah, I technically consider that cheating. But as I said, that conclusion is based on a lot of clear communication between you and your primary, as well as your consent. Did you consent to that rule?
Okay you're also saying you forgot about that rule. When you say that, it makes me think that your primary didn't communicate with you clearly at all. You certainly weren't cheating if you didn't know (remember?) that checking with him first was a rule you agreed to. You can't give your consent to something you don't even remember. And I think that if your primary had been very clear with you about that rule, then you would have remembered. I call bullshit. Your primary only thinks he told you about this rule. It is his power of recall that is failing him, not yours.
What you do know (and remember) now is that the rule in question doesn't make sense to you. Don't you think that if it doesn't make sense to you now, that it wouldn't have made sense to you earlier either? Again I call bullshit. I don't think you ever agreed to such a rule. I don't think you ever would have agreed to such a rule. Why would you have ever agreed to something that made no sense to you?
For the record, I, too, think it's a bad idea to make a rule that you'll check with your primary *every time* you're going to have sex with your secondary. Such a rule is going to be almost impossible to obey. It makes far more sense, to me, to say, "This is my secondary partner. I am going to have sex with him sometimes." And saying that once should suffice.
But I want to reiterate that what really matters here is that *you* never agreed to the rule your primary claims you did. It seems to me that he is gaslighting you.
Sympathetic regards,
Kevin T.