We always play together. That doesn't mean we both have to be in the same room or even be active participants, but we are always within range of each other.
We (like many others) have found that this very much diminishes the chance of serious emotional attachments and jealousy.
We've found too though that sometimes we find ourselves with a partner that we can react to differently (or the partner reacts differently) if the other is not in the room at the time.
An example: About a month ago, I loaned my hubby to a very inexperienced young friend of mine for her "first lesson". She was concerned that I would laugh at her lack of knowledge were I in the room that first time so I watched TV in the living room. [hubby taped the experience and then gave her the tape afterwards and said "we can destroy this right now or you can give it Betty..." she gave me the tape and we watched it together
] She is now a regular FMF playmate.
My point is that we were both present (just not in the same room)at the time and there were no secrets at all. Had she wanted to go to a motel room alone with him or to visit while I wasn't home then that would have been a no-no.
Another example of how "together" can mean different things to different people.