Hi Azure! Sorry about the delayed reply. I've been really busy juggling work, a new Soulsoft EA VN and also collabing on a game for YaoiJam 2018.
It's true, some of the endings are alittle unsatisfying but I can assure you there are definitive endings that let you know where you stand with that character. I'm guessing maybe you've only encountered the "bad" or "ok" endings like the "Friendship" Ending. Personally I like the friendship ending even if you don't end up with anyone but some people find it unsatisfying.
Anyways, don't give up! Those endings you are looking for do exist! =)