>>715404790
Noelle is an homage to Lisa.
The moss and Lancer's pocket stuff is an homage to Illusion of Gaia.
Gaster will be revealed like Beruga in Terranigma.

>>715266536
It's not like he cheats on her or anything, and they get together at the end anyway. It's a bit of a bittersweet ending for them, similar to the ending of Soul Blazer.
But yeah, he should have taken Freya with her and not left her in the constantly wet city.