Idk what's wrong about the age gap if in the end they're both single, both without children prior to reuniting, both with stable income, and both smart enough to not fuck up each other's lives.
The age gap would only be "weird" if any of those conditions I stated, or probably some other details I missed, weren't present.
Y'all need to keep your morals in check and make sure there's logical backing to your claims as to why a situation is "wrong" or "weird".
Don't start a religious debate with me either.
Also, about the physical aging "problem", they're Japanese. With proper self-care, us asians look like 15 yr olds in our late twenties and 30 yr olds in our forties. Please stop your appropriation based on your own environment.
And the artstyle is wrinkles = lines on the face = older.
Learn art before judging the artist's art.