Firstly, don't drag them around the ground. When you finish a job, walk the reel hose end rectus fitting back to your van, and then reel in.
I also give my rectus fitting a quick squirt of WD40 every morning; not inside the female fitting (the hole); but around the outside and this really does seem to increase the life of the connector.
Don't keep on connecting and disconnecting either; it just increases wear 'n' tear. Some lads never disconnect them; they have a tap either on the pole hose or the reel hose, and just turn that off; they then reel in the reel hose with the pole hose still connected.
HTH.