Struggling with plots in my book.

Several stories are happening at the same time, like crossed wires, but I still think that it is not enough for two 500-page books. Which is my initial goal.

After my last two books, realized several things:

1. I am a sucker for romance, fine.
2. I like mystery, the unknown, being hanging there for dear life without knowing what the hell is going on.
3. Pain is necessary for character development and in the end, it will help me purge my pain, so it’s mandatory.
4. Friends make life better, I want them also.
5. Smut is good, but only in the right amount and at the right place. Though I am still not sure I can write it.
6. Double POVs need to be used carefully.

With this in mind, will need to make an unexpected side plot.

What and how, don’t ask me yet. Have no idea. So I am back to the drawing board.