Dear Robert, 
I know it didn’t work out, and I know that is parting ways was ultimately for the best, for both of us. It’s so strange to have fallen in love with someone so fast, especially now that I’m not a child and know better. I haven’t had that sort of feeling since I was 16, the spark was like a shooting star; rare, and precious. I know you said there’s nothing wrong with me, and I said that I understood, but I can’t help but feel like I was too much, that I was burden. I know you mentioned that you felt like you weren’t enough, but you were. I wanted to tell you that you were and still are such a sweet and caring person, and you were always enough. Regardless, you (and I) deserve to be with people who match our energies. I want to thank you for giving me a chance, and to tell you, you were worth the chance too. Even though it didn’t work out, God you were amazing. I’ll probably look for you in the people I pursuit in the future, and hold them to the standard you raised. Of all the toxic love I’ve felt in the past, it was needed to be with someone who taught to love someone as a whole, and for that I don’t think I could ever thank you enough. 
I’ve never had an ex that I actually still respect, but now there’s you. 
– Love you, right now as a lover, but forever as a friend.
P.s.
Thanks for teaching me how to play DnD, it’s actually so much fun.