my gut feeling turns out to be always right

i have two penpals i vibed with right away mainly because our personalities matched and we had a few interests in common. the first few months we would write long letters and talk just fine, we were genuinely interested in each others life and enjoyed talking but then we ran out of new conversation topics after a while. we would still write each other, but we could feel in our letters how we were both losing interest little by little upon realizing we aren't actually that compatible. i still responded to their last letter two months ago but they haven't written back since. at this point i knew one of us would stop writing eventually so im not that affected, but it is kinda sad how its so hard to find right penpals for you. what's funny is that the only penpal that after almost 3 years i am still talking to has absolutely nothing in common with me but for some reason we just don't get tired of each other. i think this is (platonic) chemistry?? I am lucky to have met this one but i would love to have a couple more genuine penpals but it's been impossible and it is sad when a seemingly good match doesn't work out. :/