I always have a central romance in the story, so, naturally, I ship that relationship. In terms of characters who do not end up together, yes, it happens as well.
Miccola in She Kills Elephants and Men drove me insane, because I shipped her with everyone, with the MC, with two of the MC’s husbands, with the 4th husband that eventually gotten written out of the book altogether, but in the end, she just gave me the finger and remained the whoring and drinking bachelorette who left marriages to the MC.
In another extreme case, a side character refused to die—and I wrote out his death too—became the main love interest, and changed the story arc for the previous love interest, eventually changing the ending of the book.
In my current book, I was thinking about building a love triangle, but it didn’t work out because Bryn and Matteo felt like they are too stuck on one another. So, I feel that I can use the alternative love interest as a leading man in a sequel.
I have a side paring for the next book that I am interested in exploring, and I will be curious to see which relationship for the main character will intrigue people who would read it, the Childhood Friend or the Dashing Celebrity.
One thing that I want to write at some point in time is a GL book. I finally found a setting that I am happy with for this couple, but all in good time...