It was easier for Iris to cool down than Jin Liwei. She only needed to visualize the patchwork of big, ugly bruises on his back and her worry for him soon alleviated her desire.
On the other hand, unlike her, he needed to deal with a massive, raging erection which didn't feel like it would be calming down very soon. At this rate, he would probably need to hop under an ice-cold shower to force it to behave. He couldn't bear to use his hand to give himself temporary relief when she wasn't able to do anything for her own desire. That wouldn't be fair to her, and he would only feel terrible about it.
If both of them had to suffer from this abstinence until he healed, then so be it. However, he needed to think of something to tide themselves over during this period of time because both of them would probably go crazy if they continued on like this.