Burning on right side of penis mostly after sex. no redness or swelling . only one partner. what can this be?

Check up: Inspect to see wether you have a minute lesion.An abrasion,apimple.If that fails to reveal anything that might explain,you definitely need to be evaluated by your doctor

Get it checked: A burning penis needs to be examined . It could be an infection, of the penis, the urinary tract and much more. Only a complete history and exam will give you the best diagnosis. Please see your doctor.

Abrasion: Sounds like abrasion injury to the shaft of your penis. Often you might get a raw appearance in the sore area, but not always. Allowing your partner to be fully ready and lubricated should help prevent these symptoms, as well as using a lubricant such as K-Y jelly. Hope that helps.