It is usually marked by letters. Such as ababbcc. That shows what lines rhyme with other lines. There's also AABB, ABAB (shwing that line a rhymes with line a, then line b rhymes with line b. It goes line a, line be, line a, line b.
~Silver
I don’t see any examples, however, if you look at your examples gloomy is similar to sad or dreary, and the opposite of cheery or happy, so look for that in your examples