Calyx by Kenzie Kelly

She had no intention of leaving the lab. Then she stole a spaceship.

Chemist Razili prefers logic over risk and samples over standoffs, but when the Scozid-neutralizing compound she’s developing keeps falling apart at the molecular level, she makes a desperate choice: travel to a planet deep in Scozid territory and get what she needs herself. She doesn’t plan on taking a copilot. She really doesn’t plan on hijacking a fighter owned by the massive, infuriating Trelxak who won’t stop hovering.
Calyx knew the moment he saw her—Razili is his rhun. His perfect match. But until she falls for him, touching her is off the table. He’d rather go mad than risk her walking away. Now they’re trapped in a tiny ship, heading toward danger, and sharing a bed. He’s trying to stay focused on keeping her safe, keeping his pants on, and getting her brilliant, snarky self to fall in love with him. His nanites are trying to climb her like a tree.
Between malfunctioning ships, alien space bats, and a dangerously romantic field trip to the edge of enemy space, this mission is exactly what happens when a nerd tries to be the main character.

This novella is the seventh in the Ka’atari Warriors series. It has a guaranteed happily ever after and no cliffhangers, but the story progresses from book to book and the series is best read in order.