Aliens Hijacked My Heart by Hawke Oakley

The only thing Jaeyoung loves is science—until an alien hijacks his heart…
Jaeyoung was never supposed to crash-land on Eukaria, but now that he’s there, he might as well make the most of it. As both a doctor and engineer, he’s hungry for knowledge, and his new alien home is brimming with discoveries, including the big shocker—Maeleons can somehow fertilize human males.
Compelled by scientific curiosity, Jaeyoung decides to unravel the mystery of alien-human conception. But it takes two to tango, and he needs a partner to dance. Fortunately, a doting Maeleon called Linn’ar is happy to rise to the occasion… over and over again.
Jaeyoung wants cold hard data, not a romantic relationship. But through his plentiful experiments with the alien, Jaeyoung realizes he’s fonder of Linn’ar than he should be, and the adoring way Linn’ar gazes at him certainly isn’t helping…