I guess for me the part of establishing effective communication with your partners is the "meta-communication" - the communication about communication.
It is, in my opinion, vitally important for you to get a very clear understanding of what matters to your partners. Don't be in any doubt whatsoever. Without this you are going to have a constant battle with yourself over whether you are doing right or not.
So, for example, if your partner doesn't care one way or another whether you kiss someone at a party, then not telling them when it happens wouldn't be a serious omission. If, however, that is something that is very important to them, then not telling them takes on a whole new meaning.
I really don't think there is a "one size fits all" when it comes to this issue - you have to really understand and know your partners' preferences and needs.
I would suggest that if you can't or haven't had that conversation with your partner(s) yet, then you are asking for trouble down the road.
For the record, I happen to think that this is a lot of what is wrong with "standard" monogamous society - the "rules" are these undiscussed, so-called "commonsense" thing that more often than not gets people into trouble. If couples would just talk about this, it would solve so many problems!
"Listen, or your tongue will make you deaf." - Native American Proverb