i was hoping for a generally upbeat romance where the love interest is a demon girl- maybe like an oni or something. some sort of forbidden romance or uncertainty would be a plus but not required

maybe something with the vibe of like Onikirisama no Hakoirimusume before they rushed the ending- except little more romance oriented and less shounen-y.

my only major qualms are that theres no mecha, horror, smut, rape, tragedy, unresolved harem, or one shots- and that the art be 'good'

being complete is a must.

Here you go: http://www.mangaupdates.com/series.html?category=Demon-Human%2BRelationship&genre=Romance&exclude_genre=Hentai_Shoujo%2BAi_Shounen%2BAi_Smut_Yaoi_Yuri&filter=scanlated&perpage=50

Might want to loosen up your criteria a little.

Eh, the category doesn't differentiate between male and female demons (why is there no "demon girl/s" category? o_O

The only thing coming to my mind right now is Superior.

[img]http://www.mediafire.com/convkey/a8ee/v1c0uzwpt6cdtcbfg.jpg[/img]

using tags rarely works for specific stuff like this- which is why i asked for recommendations. im not stupid- its just that half the tags are nonexistent and there are a crapload of manga that arent tagged properly, and if you just go by that without asking what other people have read then you wouldnt find half the manga out there. ya know?

like- if you searched by tags then you wouldnt even be able to find the one i mentioned in the op because the tags are so vague or poorly done- they tagged it with 'human weapon' which doesnt really fit that well, but didnt even bother to tag it with 'human-nonhuman relationship' which is one of the main premises.

my criteria really isnt THAT specific- im pretty much just looking for completed romance manga with a demon girl--- which you cant find because the tags are nonexistant

Urusei Yatsura is the only thing I can think of that sorta fits your criteria, Lum is an alien, but it is a upbeat romance and the harem is resolved.

Ao no Fuuin

I'd suggest My Balls, but you're not looking for smut. It's very cute though if you can stomach borderline-H.

Maybe Princess Lucia - fits all criteria except maybe one. It has demon girl, forbidden love and stuff but it's a harem and not sure what kind of end there will be (though I guess, there wont be a "typical harem end", cause its not the usual harem comedy focus, there are feeling towards some character and other stuff).

Try Kanokon, it's a funny upbeat romance, though its very Ecchi. I highly recommend you give it a try. Though my self haven't finished it so I wouldn't be able to tell you about the end, I'm on 29/49 chapters

Beware the Fox, for while he is wise, he is also mischievous and cunning!
[img]http://puu.sh/dn6tb/f47075ed31.png[/img]

maybe
Outlanders
Lilim Kiss
Akuma Jiten I didn't read this so I don't know if the harem is resolved

[img]https://c1.staticflickr.com/1/753/22668593615_519ce54b81_o.png[/img]

I second Ao no Fuuin and also suggest Superior