The facts have been discussed on the show. And it's not just Tom. Luann said -- on camera -- that she had an open relationship with her husband but, when asked about it on the reunion, she denied having an open relationship and denied having ever said any such thing. It's ridiculous.
I do think you should warn a friend if you have knowledge about their fiance/husband being unfaithful, but, once you've done that, you need to step out. I actually don't understand why Luann seems so desperate to be married to this guy -- it borders on obsession -- but, if she's determined to overlook any