There are always going to be people like that. Those great relationships that we ruined somehow, or those ones that we can always look back on fondly despite how regretfully they ended. It's possible to have smooth relationships that end, but they still end for a reason; maybe it's because one or both of you needed to grow, or you were just in different stages in life. You mentioned that he's searching for himself - everyone needs to do that at some point, and it's difficult to do when you're also with another person, because then you're not sure if you're finding yourself, or someone that's part of a relationship.
It's not bad to have those feelings for someone you've been with, but you have to remember that it's in the past, and sometimes we hide away there when neither the present nor the future seem very inviting. Good or bad, you're better for the experiences you've had, and now you know better. Although, you might also be feeling regretful right now because of the current "relationship" you're in (if you're still in it), using a past relationship as a standard for the current one - don't do that. Each relationship is different than the next, and first things first you need to communicate your concerns with your partner. If they aren't vocal, then...maybe it's about time to let go. Don' be afraid to let go of a possibly toxic or useless relationship just for fear of being alone, because you never are, you've got friends and family who will always have your back. I know I myself will be prayin' for you, even though I don't know you beyond the words you type here, I care about any person finding happiness, because it's a universal feeling that transcends everything else. You've got my support.
However, if you truly think your guy from Hawaii is "the one", then reach out and communicate more, but don't just jump headfirst thinking something good will come of it. Don't think your past relationship with him will instantly have any bearing on a second attempt, you're both different people now, so it's time to see if you're both up for it, and whatever hardships come.
Also - try not to think about "the one" as someone who you can meet and then lose. The one is not a person who you could pass up in your life, it's the one who will be there for the rest of it.