I can offer a few love triangles with no betrayal and no massive melodrama. But there are way different kinds of romances...comedy, dark comedy, historical, fantasy, action, scifi but maybe read the synopsis and decide if it's your type.
I don't mind the triangles as long as there is no betrayal. I'm also a totally happy ending girl as well and hate anything to do the cheating and wishy washy back and forthers that don't know who they like. Loyalty is a must.
If you liked Your Beautiful (I own it)you might like:
Ikeman Desu ne - the same as YB but not the same. Some is better some is not but better ending.
Sungkyunkwan Scandal- (I own it) first episode not very entertaining but so funny and cute afterwards. There is one other girl but not bad and no interest, happy ending
I would say Coffee Prince but you dropped that one
yamato nadeshiko shichi henge - I bit silly and youthful but cute and funny...there are no triangles but the romance is a lot more subtle
To the Beautiful you - youthful but very cute and sweet moments...Oh but there is a girl that causes trouble like in YB but the guy so doesn't dig her so it was ok by me. I personally liked it better than the other versions but that was just me. Happy ending but could have been better.
Chilling Romance - movie, a mix of comedy, horror and romance. The ghost freaked me out a little but the romance between the leads was cute and sweet and the end was happy
Greatest Love- I don't remember a triangle and the ending was happy ending girl ending
