Thank you for stopping by, and for giving Love Hues a try! :D I'd be happy to share a few hints.
If you've only seen bad endings so far, it's likely an issue with his affection points. Devlin's route's tricky in that there are several checkpoints where not having enough points will lead to a bad ending + his choices are more grey than most of the other characters. Selecting 'Fine Arts' as a field of study at the start of the game will give you a little boost to help you in this regard; check the affection points meter often as you navigate through the game and this should help you.
Another critical event is that Devlin should mention a gala after the ice fest, and the final scene in his route also has several key choices.
Please don't hesitate to let me know if you get stuck anywhere else!