Neither Pennsylvania nor Connecticut makes marriage records available to the public. You can try requesting the marriage record using this application form (often they will look even if you don't know the date of the marriage):
http://www.ct.gov/dph/LIB/dph/hisr/VR/vs_39mst.pdf (for Connecticut)
Both of their obituaries say they moved to Connecticut in 1966.
However, they aren't listed in the Connecticut Marriage Index through 2001.
Pennsylvania doesn't maintain a state-wide database of marriages. You have to know the county a couple were married in. I've searched all the counties that have published records in the 1970s through 1980s (only about 25% of them are available, and Bucks Co. isn't among them)) and they aren't listed in those counties.
The Social Security record for Katherine shows that on 12 Aug 1983 her name was Katherine E. Kenerdine, so her marriage to Coleman was before that date, and after his divorce in Feb 1975.
I've done a search for them without any geographical information, and if there were a marriage record available anywhere in the world it should have shown up. Keep in mind that most entities don't release marriage records to the public for anywhere from 50 to 100 years.
Please let me know if you have questions.