My ex and I have co parented DD (14) for the last 6 years - despite our differences, we've negotiated the major hurdles (secondary school selection, first mixed sleepover etc) but as she's growing up into the normal, challenging teen stage we seem to have very different approaches.
As far as I'm concerned, DD is a pretty normal teen - we've had very few issues, but there have been repeated incidents of mislaid school letters/reports and issues around her personal hygeine - in particular the disposal of sanitary products.
I've been pretty detached and matter of fact about these - yup, these things happen, but I do follow through on "natural consequences" and am unmoved by her tears and tantrums (when, for instance, I call the school to ask for a copy of the letter/report she has lost, or ground her until her room is clean). I ignore her accusations that I'm the worst parent ever and I don't bear a grudge - she makes a mistake, we deal with it, move on and learn from it. We have a very good relationship; she confides and debates with me, and we spend lots of positive time together.
Her Dad favours the "I'm so disappointed in you" approach - followed by a compensatory gesture (last time it was an iPod) after a shouting match.
He copied me into an email he sent her today reprimanding her for not disposing appropriately with sanitary items at his house that his DW subsequently found. It includes a photo of the offending items and it's littered with references to how he feels about it. He has asked that the three of us (me, him and DD) meet before Xmas to discuss it further.
I'm wondering if the lack of consistency in approach is going to be a problem long-term; I tend to expect this kind of behaviour/attitude from her as normal teen stuff and deal with it as it arises without getting upset and emotional about it myself, but he seems to take her mistakes/teen attitude very personally.