My cock ring doesn't hurt at all. You can buy rubber sealing rings at any engineering supplier that sells bearing and seals. (Don't tell him it's for your cock though) Metal ones are very expensive but very good and usually the girl likes to play with it.
I do earnestly recommend a PA (Prince Albert) ring in the end of your cock - not too big. It looks fabulous, the girls love licking and sucking it and it's like having an extra inch. They're easy to take off if she doesn't like it.
It's not painful as it heals, if you don't move it. I used a toilet-roll former round it for a couple of weeks, taped down to my body. Loose trousers needed. Never mind a big cock, you get girls texting you and asking to see it.