Sky Song by Lydia Hope

After a dismal upbringing on decaying, alien-infested Earth, Emmaline “Cricket” Beatty now lives a charmed life on humanity’s new and improved home planet Meeus. A constant vulnerability of the before has given way to an ironclad security of the present. Everything is pretty, organized, predictable. There are no flaws in this new world.
When the hospital where Cricket works hosts an intergalactic symposium, she is called upon to translate for the alien guests. She is intrigued to see that a secretive Rix nation has sent a delegate. Lyle is far from a cold-hearted, humorless killing machine like the Rix Cricket has heard about.
When Lyle gets stranded on Meeus, Cricket shelters him, violating Meeus’ anti-alien laws. She’s drawn to this vulnerable male by a combination of compassion, curiosity, and her own loneliness. They develop a friendship that teeters on the verge of becoming something more, except Lyle’s persistent questions about the hospital and medical research conducted there make her increasingly suspicious.
Before too long, a string of seemingly unrelated events happening around Cricket begins to pierce the cocoon of idyllic perfection she built for herself on Meeus. Nothing is what it seems, least of all her new friend Lyle who is using her to search for answers. His quest makes her doubt her own sanity as it puts her in mortal danger, and he is the only one who can keep her safe.