And I've discovered that I have no problems licking up after a ruined orgasm, and in fact enjoy it quite a bit. But not after a full orgasm. Then I find it repulsive. It's funny how I feel so different in the two different situations.
THAT is the whole chemistry of why chastity denial works.
Your non orgasmic state is high in the 'happy hormones', Serotonin, Oxytocin and Dopamine.
When a male orgasms with a climax, the levels of those hormones are drastically reduced and replaced by others, which cause you to go off sex and have a "downer". It can take hours, days or even a couple of weeks to gradually return to the previous "happy high".
This is result of our evolution.
Males are more likely to ensure the survival of their genes to future generations if they have multiple partners. So, once you've impregnated a female and have had that happy experience of an orgasm, it's time to move on to another female to increase your chances. If she was fertile and you've given her your sperm, there's nothing more for you to do. Losing your happy hormones for a short period makes it easier for you to move on and keep spreading your genes.
In the modern context, not having a full orgasm maintains your happy hormones, which make you more likely to stay with and be devoted to your partner. Because you don't go off sex she's also much more likely to have multiple orgasms, just having one orgasm every time she wants sex can be sufficient benefit.
You are happier for longer periods of time because you don't lose your happy hormones, and she's happy because you stay attentive to her for longer periods of time.
Win-win for both of you all as a result of avoiding that male hormone disruptive full orgasm.