Hi again Maarten,
A few further comments.
In your first post you talked about "selfless (non-ejaculatory) sex". I'll be fully honest and tell you that I practice Devotional Sex because I find that it gives ME greater pleasures, satisfaction, excitement, and intimacy. So you could say that, even though I have fewer ejaculations, because I'm choosing to do this, and I feel I'm a winner, what I do is selfish
Of course the only reason I've found so many women who have enjoyed Devotional Sex with me is that this technique has huge rewards for my partners as well.
I very much enjoy receiving pleasures, and I find that with my higher erotic energy from fewer ejaculations my enjoyment of receiving pleasures is much greater. But a key to the success of Devotional Sex is that I also enjoy pleasuring my partner. If we have a session where all we do is me give her oral sex and then end with a cuddle with her holding my erection, she clearly enjoys this. But I have enjoyed giving her oral sex, and I absolutely love it when she takes hold of my erection when we cuddle, and I really enjoy the intimate cuddle powered by my high erotic energy and desire for her.
So the secret of success of Devotional Sex is that it is WIN-WIN.
I think that win-win is the best way to present this to your wife. You should make clear to her that part of any exploration of Devotional Sex is finding out what SHE likes. When you make suggestions of what can happen with Devotional Sex it is important that you mention anything that you think she might like, even if it is something that you might not particularly like.
If you give her the impression that it is all about HER, then she may feel rejected as a loving wife who wants to please and pleasure her husband. So let her know that whilst the first bit of the definition of a Princess is that she uses her power over you to have fun and enjoy sensual and sexual pleasures, the second bit of the definition is that she must keep you eager to remain her Knight. Part of this is giving you the standard sexual pleasures, but over time you can let her know that some things that make you feel under her power also give you great pleasure.
A benefit of her keeping you horny is that you will always be eager to give her sensual pleasures such as a foot massage. For her receiving a foot massage may be just relaxation, but for you it will have some sexual energy. If the kids are not
around, you could let her know that it would make you feel much more hers if she sometimes had you be naked while you gave her the foot massage. Perhaps your wife will love the idea of having you be naked. But perhaps she might make you be naked every once in a while mainly just to please you and make you feel like her Knight.
Giving your wife a foot massage in the living room (with you clothed) is the sort of devotional activity which you might feel is ok to do when the kids are around. And it has a side benefit to a Knight that a foot massage relaxes a tired Princess and this makes it more likely that she will feel like some sexual activity later on.
As you say, the next big step is to try your first formal Season of Devotional Sex where you promise to obey her sensual and sexual wishes, and she decides when the Season will end by having you ejaculate.
Good communication is important, so it is good to discuss with your Princess how you feel about ejaculating. At times you might say "It is challenging, but I would really like to go a day or two longer", or "I think I really need to cum tonight". Very often your Princess will take your advice.
If you do several Seasons you will find a time when you really want to keep the Season going but she decides to end it by making you cum. That is an important part of her power.
A very powerful moment of truth will be the first time you say "I'm desperate to cum tonight" and your Princess says "Not tonight, I want you charged up for at least another day".
Of course you need to agree that starting a Season of Devotional Sex means that you cannot make yourself cum without her permission. If she looses interest at the end of a Season, it is best to tell there that you need to cum, and say that if she allows you to cum, you would prefer to share it with her. Let her know that it is ok for her to tell you to play with yourself to make you cum."
Don't make a big fuss about commands. I have found that it works well if you tell your Princess about the Ritual command, and then when she asks for oral sex the long way, just remind her that all she needs to say is "Ritual". Once they have used the command once or twice it becomes a natural and easy way for her to tell you eat them, and her using a whole sentence seems far too wordy.
I've probably said far too much, so forgive my keenness to help you take the next step.
I look forward to hearing how thing progress. Happy exploring!