The Protector. Stargazer Series, #4

Neo has just made it back from a dangerous mission protecting innocents from a vicious alien species. He's ready to take it easy for a couple years. Have a little vacation on the new breeding planet they call Earth. Jessie Ashby has worked among countless Stargazers since they landed. She wants a mate of her own. Unfortunately, every Stargazer she's met treats her like a precious little sister. Until she meets The Protector.
It figures the one Stargazer who's finally attracted to her is just here temporarily-and looking for a casual romp in the hay.