I can't see any other likely deaths for George, and he doesn't seem to be on later censuses. (Some "widows" were in reality just separated from their husbands at a time when divorce was complicated and expensive.)
According to Cheshire BMD, the George ALLEN who died in 1845 was aged 30, which would fit, so I wonder whether Dinah fibbed about the father on Frederick's birth cert?
The other possibility, of course, is that he died in another area for some reason, but that will be hard to verify - his name is not uncommon...

Rambler