Hello Kris
a couple of ideas - probably not super helpful
1. Given that they did not marry & the parents disapproved, it could well be that Charles was married to someone else - who may not have died as early as Rose. I HATE suggesting/using 1837online because you can spend a fortune, but either thru that or alternatively lots of time searching St Caths find any marriages for Charles A Cullen. I assume you have his death certificate -although spouse /children details are not given (I am used to them in oz), sometimes the informant can be a relative which may provide extra information.
2. Is your newspaper report the funeral notice? If not, can you find same - Family members are often mentioned.
3. I had a browse of the 1881 Census - There is an 1877 Charles Cullen, born Liverpool whose mother was Irish and an 1880 CC with an irish father.
4. Have you tracked the four children or their descendants. There could be some hidden information. I have found in my families that often the oldest or youngest child will end up with the family "heirlooms" - photos, family trees, inscribed bible etc.
5. Maybe you will need the 1911 census (only another 7 years!)
Trish