You have given it a good go OP, because he is nice and kind and you enjoy his company.
I actually respect that you have given it some time, because sometimes, those feelings can grow into amazing relationships, and I do think that some people 'sack someone off' really quickly if they don't get instant sparks instead of taking their time and seeing if there is something there.
Nice, kind men don't come along often so it's good to give it a go. However, 8 months is a long time to figure this out and I am sure you have known for a while that this isn't really going to go the distance.
You need to call it a day.
I had to do the same thing in my late 20's. Met a guy who was perfect on paper. Treated me well, my family loved him, we shared the same interests, he was nice and kind. But I just knew, after about 4 months in, that I wasn't falling for him in the way that I would have expected to.
It is hard sometimes, because at the back of your mind you are thinking 'what if I don't meet anyone else this nice and kind and regret it someday?'
But on the flipside I didn't want to keep going in a relationship that I knew was ultimately going to make me unhappy and it certainly wasn't fair on him to keep going with it.
Be brave, rip off the plaster, and have the talk.
Good Luck op x