
Wait I don’t get it... he’s not immortal.. ok. Then how come he hasn’t aged for 60 years? I’m kind of confused about the explanation..

I think its more of him being a guy than a woman. Since its impossible for him to give birth, the spell cast on him doesn't grant him total immortality. That's why he also gave a part of his horn during the 59 years that he was gone to atleast sustain the spell. That is also why I think that he aged though not 59-year aged from the moment he met the mermaid to now.
Why'd they have to ruin the good vibes from the beginning by ending the chapter with the gross husband and his ugly hoe(/TДT)/