I love sports manga and love romance, but the two don't go hand-hand. Anyone know one with?

Virtually anything Adachi Mitsuru. (Almost, and even the ones that don't, usually have a hint of sports in it)

I guess, there should be quite a few romance Mangas with at least a sports related setting, like ...

• I-Revo - Ice Skating
• Chihayafuru - Competition Game/s
• Kimi wa Kirakira - American Football
• Sorairo Ageha - Tennis
• 23:00 - Dancing
• Hanazakari no Kimitachi e - Track and Field
• Kanojoiro no Kanojo - Mixed Martial Arts
• Kimi ga Suki and Power!! - Basketball
• Tetsugaku Letra - Basketball and Dancing
• Aozora Yell and Taiyou wa Kimi ni Kagayaku - Baseball
• Samurai Baby - Kendo
• Purikyuu - Archery / Kyūdō
• Suiren, S.P.Y and 18 Diary - Swimming
  ... ^^"

"It's like love is a bonus in your life. Even without it, I'm just fine. I don't feel like pointlessly searching for it. You don't have to make yourself unhappy." (Ookami Shoujo to Kuro Ouji)

"Why does it rain?" - "To create drama." (Drops (Andou Yuki))

Suzuka

Crimson Hero - Volleyball
Aoi Kiseki - Swimming
Uwasa no Midori-kun!! - Soccer (smut)
Sugar Princess - Ice-skating

Suzuka <- (Completed) Track and Field. More of a romance with a big sports subplot
Baby Steps <- Tennis. Slow progress romance

Technically Good Ending is a sports manga. I rarely see them play tennis though. It's definitely more about the romance. And the harem.

I second Crimson Hero and Kimi wa Kirakira. I enjoyed both of them for their sports and romance elements.

And so Man Candy fell in love with Vampire Mermaid.