
Huuuuge Spoiler Warning!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A loooooong time ago I saw the raws, sorry I can't provide the link as I can't remember it I believe someone posted it on one of the comment pages below. Okay so here's the spoiler so basically from what I remember the MC does return and there is a moment where the two are separated but ( if I remember correctly) the mc goes to the puddle/pond in her backyard and remembering Suijin and I think she either calls him or she cries.
Anyway she does something which causes Suijin to enter her world the two reunite, so it is a happy end, I don't know if her family sees/meets him as the latest raw I saw at the time that is where it ended so don't worry this story won't end as a tear jerker.
Unlike this author's previous work Reimei no Arcana where one of the guys I was shipping or wanted to ship with the MC ended up dying. Soooo sad I am still crying rivers of tears from that scene! ┑( ̄Д  ̄)┍ (/TДT)/

Didn’t that happen already???? That part that you mentioned where the main character goes to her own world and the pond and calls him..... I haven’t read this in a while so I’m not sure... plus I’m a curious person who loves spoilers so maybe I looked at the raws (tho I don’t think I did)
I’m think that happened already or does it happen again???

Yes it happens again towards what appears to be the manga's finale as there is a total of 47/48 chapters.
This happens in the latest chapter 47.... or was it 48? Sorry I will have to recheck, anyways I was bit wrong where she calls him as I reread it basically Suijin seems to be in a deep sleep and the MC is thinking back on him from the previous chapters ( or at least it appears to be that from what I got from it, I can't read Japanese) and she puts her hand in the pond and Suijin grabs it which wakes him up and pulls him into her world. (๑•ㅂ•)و✧ヾ(☆▽☆)
And the two reunite as Suijin picks her up and the two look lovingly into each other's eyes and that basically ends it. ε=ε=(ノ≧∇≦)ノ
I feel a tragedy coming... We all feel it.... I feel like Suijin will die or start to die or the mc will go back home