I don't think this is the manga previous anon was thinking of, but in Shout Out Loud/Sakende Yaruze, the main character's son plays ice hockey and has a crush on his coach. I don't think their relationship ever got resolved in the main plot arc -- the mangaka may have been planning a spin-off series? (if it ever got written, please tell me where I can find it, coalie! I've been wondering what happened to Nakaya for years.)