The 'partners to friends' route can be frought with misunderstandings and communication breakdowns. this behaviour could be a number of things - he still fancies you / thinks you fancy him / doesn't fancy you but thinks you fancy him / is jelous of a new partner / wonders if you are jelous of his new partner - the list just goes on. If you are comfortable talking to each other, pick a suitable time, and gentrly bring up the subject of how you feeel about each other, but go carefully, once the genie is out of the bottle ....