Well yes Ash says he misses an old friend very much. Then you got Brock falling in love with just about all the Nurse Joy's and Officer Jenny's from Kanto to Sinnoh. Kenny has a crush on Dawn. Though they never show anyone getting to serious in the series. There are also fanart that shows Ash with Misty/May/Dawn/Iris depending which ones you find.
Edit: There yes and no in the movie Pokémon Heroes: Latios and Latias, Bianca/Latias kissed Ash on the cheek but nothing other than that unless you count the multiple times Brock has tried to kiss a girl.