there're only Finne and Elna as Arnold's potencial lover. Other girls have appeared like a princess who falls in love if Arnold disguise as Leo, Sofia (a half elf strategist), Mia (a Thief from another country), Lynfa (the adventurer tomboy we saw in the first chapters), a SS-rank adventurer and now a grandaghter from a noble who Arnold admired, but fortunutely none of them became a member of Arnold's harem (only 2 member haha).
Actually, we saw very little about romance development when it comes to MC, some side characters get more romance development, like Leo and his first crush, a Saintress from another country or Lize (Arnold's older sister) and some Duke.