Wow...that's a lot of issues for a simple question. I would suggest you have a relationship to fix first before worrying where you end up with a lover.
As far as the actual question, For myself we ended up buying a condo in a nearby city for a variety of reasons, one was to make it our little sex den but you could always meet at their place. We met people that had common interests, my wife through her gym, me through a non-profit society.
Here's a thought and i'm trying to not make assumptions but you tend to have to in a forum. If you're going to be poly it's all about trust, openess and honesty. Obviously there's a reason he's not wanting sex, be it medical, attraction some sort of hurt etc. Can you be open and understanding and focus on him even if your feelings get hurt? Maybe even ask him to email it to you ao there is no emotion or less emotion. The trick is getting to the root of the problem and tackling it instead of the jealousy or hurt. E.g. If he says, well you've gained a lot of weight and i just don't find it attractive. One response could be .....well you asshole, you're no spring chicken either tubby!!! Or, you could say, well obviously it'll take some time to change that but i'm willing, if you are there to help me. For every milestone we reach i want you to plan a nice romantic evening.
That example is a little harsh but it was to demonstate that openess can sometimes be blunt. You have to take emotion out of it or it just becomes emotion feeding on emotion.
Goodluck, my other thought was maybe go to a swing club instead and use the sexually charged atmosphere for rekindling, discussions but don't plan on doing anything.
I'm new at this though so take it with a grain of salt. I also have a great relationship to start from.