Plot points are the individual events that propel your story arcs forward. Ideally, they should change the status quo in some way. For example, when your two main characters share a first kiss, that event changes the course of their relationship because they now must acknowledge their romantic attraction. Or, when the worst thing that could happen to your main characters does indeed happen during the dark moment, it tears apart their relationship.
All romance novels will have the same basic plot points:
Introduction, or cute meet
First kiss/First acknowledgement of attraction
First love scene/First acknowledgement of emotional commitment
Resolution, or HEA
As previously discussed, the subplot must support and advance the main story — the romance between your main characters. While a category, or series romance, may not have a subplot at all, a single-title romance could have several, although the integration of the different story arcs into the main plot should be just as seamless.
Although every romance novel may have the same basic plot points, each book is different. What makes a romance unique is the specific details of each plot point and how each point fits into the story arc of the novel.