You know, personally, I think Bolin should be one of those characters who has a new love interest every season.
Book One: He’s crushing on Korra, fanboying over her, she doesn’t return the affections, his little heart is broken.
Book Two: He goes and flirts with Eska, winds up hitting on her brother, has an awkward romance, those two end up going back to the North Pole.
Book Three: He learns metalbending from Lin, while he’s working with her he develops a crush on her, realizing that she’s a really attractive old lady. He finally musters up the courage to ask her out/kiss her and is shot down spectacularly. OR she promises to go on a date with him if he can sweep her off her feet. The thing is that he has to do so using one of the metal cables. Epic battle ensues, he actually succeeds, they go out on a date, things don’t exactly work out.
Book Four: Jinora sticks her neck out and asks Bolin out (after chasing him for the last two books), epilogue shows that they hooked up and wound up together after all.