Is there a way to say this without hurting him that much?

I used to be in love with guy A and a lot happened, he kept leading me on for 4 years until something really bad happened that made me fall out of love with him completely (there were already many tiny things that started this) and after talking about it we ended up being good friends, I got his reasons, he got mine and all of that. A month after that, I met guy B and he is such a nice boy to me and it's obvious how deep in love he is with me (he told me he's been in love with me since last year but he wasn't brave enough to approach me at school at that time). We started dating a month after we met each other to see if things would go well between us and even though I don't feel anything at all for guy A, I cannot reciprocate guy B's feelings either, I really just can't. I feel like all emotion was drained by guy A, just like Tom Odell's song "Another Love".

"And I wanna cry, I wanna fall in love
But all my tears have been used up"

Maybe it is because I rushed things (I didn't feel like I was until I saw guy B was falling harder in love with me when I could just like him as a good friend) or I don't know, but the thing is that I don't want to make guy B suffer a lot but I don't know how to say it in a way that will not hurt him so much because it's anyone's fault really, not even mine, the fact that I can't feel anything for anyone right now. We're such a good match and all but I just can't feel that way for him even though I gave it a try and I don't want to stretch this any further.
Is there a way to say this without hurting him that much?
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