For me the key defining thing that makes something a romance, outside of the whole HEA / HFN ending, is this:
Can the book survive without the romance in it? If so, it's not a romance. A romance novel, regardless of its subgenre, must have the romance beating at its heart. It must be the center, the core, the soul of the story. That doesn't mean that two people must sit on a couch staring starry eyed at each other. But it does mean that the romance must be important in such a way that if you took the romance out, the book would not function.
Think of it like this: what do you want your reader to be thinking when they pick up your book? Ex. "Gee, I'd really like to read something where...?" and think about what your book does. What are you trying to give / promise the reader?
From the way you have described your book *here*, the draw for *me* would be wanting to read about someone picking up the pieces after the loss of a loved one. The romance with a new man would be something I would view as hopeful, a symbolism of growth, the continuation of life, and forgiveness. But it wouldn't, as described, be the reason I would buy your book. Which means I wouldn't be buying it for romance (as described to us here).
I hope that makes some semblance of sense.