Inspiration can come from anything. A picture. A drawing. A dream. I have written an entire story based off one perfect line that came to me in while waiting to checkout at the grocery store. You never know where inspiration will strike and I can't tell you how many amazing ideas I've lost in the ether of my brain because I didn't write them down.
Do yourself a favor.
Write your ideas down... in a notes app. A voice message to yourself. Anything. There's nothing worse than sitting down to your computer and strumming your fingers across the keys while you try to remember this amazing idea from two weeks ago that's just... gone. It doesn't matter how good the idea is. It can still be forgotten. Write your shit down... trust me.
Now if you're wondering about my specific inspirations... well... most of them come from sex. I don't write love stories. I write about sex. Sometimes (not always) my characters will fall in love, but I don't usually start a story with love in mind. I generally begin my relationships the same way so maybe that's a me thing. I know a lot of people that are looking for love but that was never me. 'Love' only ever happens by accident for me and I usually fight against it, tooth and nail. Most of my characters tend to follow this pattern as well.
So... what's sexy?
I can't speak for anyone else, but I find a lot of things sexy. So many things. In fact, I believe almost anything that isn't gross... can be sexy. One of my most popular stories came from someone betting me that I couldn't make changing a tire in the rain, sexy. I still am not entirely certain how that story became what it has, but that's probably because I don't sit down and write traditionally. I rarely block out my stories ahead of time. I don't do any outlining (for shame). I just write... I let the characters take shape in my head and write their own stories. This will not work for everyone. If I'm honest, it doesn't really work for me most of the time, but it's the only way I know.
Writing is a craft, and mine comes from my mess of a mind mixed with bits and pieces of everyday life.