I believe this is a case of mistaken identity. The William House who married Bessie Rabbetts and went down on the Titanic was, I believe, William C House. If you go to my website dedicated to people named House, Howes and other soundalike names and click on this link ... you will see a thumbnail image of his marriage certificate. I'm afraid the full image is not displaying correctly at present and I'll fix it, BUT if you hover your cursor over the image you will clearly see that he was age 26 when he married, not 19. The William John House to whom you refer was indeed born in 1874, but I believe he died in the same registration district in 1880, age 6, which explains why he didn't appear in the 1881 census. Happy to engage in correspondence at the email address supplied or via my website.