I don't feel the same way for my boyfriend anymore and I don't know what to do?

So I've been dating a guy who started off as a friend for about a month now, and I had had a crush on him for at least a month or two prior to dating. He had a girlfriend at the time so I didn't intend on doing anything about it, and even when he broke up with her I still decided to keep it low key, but he ended up making the first move and I was honestly really, really happy. For the first few weeks it was perfect, he is a complete sweetheart, he gets along so, so well with my family and friends, and he and I just work so well together in general. He told me he loved me after only a few days of dating, and I reciprocated because that's how I felt at the time. But only in the last couple of weeks have things changed for me.. I seem to have lost the spark while his seems to be fully ignited still. I don't feel the same way about him anymore, and I feel absolutely terrible but when we're together our time seems to drag on, I don't enjoy getting very cuddly, and I don't know why but I actually dread kissing him... I feel so, so bad. I don't know where this is coming from and I wish it wasn't like this, but I've been really trying to push the negativity out but I can't seem to bring myself back to that point of being happy with him and wanting to build on our relationship. I know this isn't even a good reason to break up with him, but it's not fair to drag him along if I'm harbouring feelings like this. What do I do? How do I end this without hurting him too much?