Correction, Basara did have a romantic interest, but she took off into another dimension assumedly never to be seen again. Say what you will about Basara, but he came as close to showing interest in Sivil as was possable for him to show. Of course that was more of a love mishmash with Gigil unrequitedly chasing after Sivil, Mylene unrequitedly showing interest in Basara, Gamlin unrequitedly chasing after Mylene, etc. And super hot hyper destructive few hundred thousand year old space pixy technically counts as the mature female in that relationship
Also, had Pedro not been there, I'm pretty sure Basara would have tapped Emilia. Hell, I would have tossed that kid in a giant bra & locked him in a closet for a few hours.