Short Term Relationships and the inability to commit

I think the title says it all. I am fitness relationship disaster. Like my dating life was in my 20's I am streaky and sporadic fitness guy. I go full tilt in love with the gym, running and healthy living for 3 or 4 months at a whack and then I bolt. I know it sounds funny to compare it to a relationship with a girl but its pretty darn on the money for me. I get so close to a goal and then boom I leave her alone and crying. I am talking about the gym and my workout habits here so don't stone me yet.

I want to weigh about 165. Over the last two maybe three years I have gotten so close at varying times. Then I get distracted by beer, my social life or the holidays come along and with that food and a work out day skipped here or there. Before I realize whats going on I have not, ran, worked out or eaten something non fattening in 3 months. Seriously look at my endomondo and it will reveal my dirty secrets to everyone.

So here I am again on an upswing again. Ive been running for almost a month and plan to woo the gym once more if she will take me back but I need help.

I need to lose 20 pounds and I need friends to help keep me committed to a relationship. Who can be my wing man or woman? Who is willing to deal with a guy afraid of a long term relationship.