@Velsy Part of his terrible decision making is because the item descriptions are faulty.
According to text, the bow makes the target fall MADLY in love with you. If you ask me (and especially with the setting of this universe), "madly in love" means full-blown heart-shaped pupils "I'll do ANYTHING you ask of me".
Sensei's just mildly crushing on him. I'd have used the bow too.
Also, he replenishes 5/5 arrows per re-entry, so each arrow he doesn't use is wasted.
Then, with Akitsu. I'd say the smart thing to do would be to let her come home, get called by the dungeon, shoot her, make her fall MADLY in love and order her to never speak about it.
But since description is bullshit, and we don't see how exactly it works, it makes sense that he tries to keep her away.