To quote a favorite author, "generalities are always wrong". There are quite of few of them being bandied about here. Some sour grapes and hurt feelings, and that's a shame.
I wish the topic of enemas were the only challenge a married couple faces. My wife and I have been married 36 years, and over that time, we've faced a few. But we're together, and our relationship is strong. We're actually more playful and unfettered than we've ever been. Some lessons in life are hard, but if you seek to actually learn from them rather than defending your pride, even at a late date, you can be a better person and a better partner.
The original question is whether we should "risk" a relationship by revealing our interest in enemas. I know that for the majority of us here, enemas are a significant component of our lives. I fear there would be more risk in trying to conceal something of such major importance to us. Of those I've talked to personally who have tried to do that, conceal their fetish, it hasn't worked out well. It's nearly impossible to hide, and I have to think that trying to do so will only cause you frustration and resentment; our partner doesn't like our hiding aspects of our persona, that's natural. Relationships are all about trust.
I do think that the way we approach it with our partner is crucial. If you present the concept with an air of shame and embarrassment, that vibe is likely to transfer and be obvious. Our sex lives are seldom more playful than when in the throes of new love, we're learning about one another, and, it's very possible your new partner has never formed an opinion on the subject of enemas. It's not a commonly discussed topic. That was the case with my bride-to-be, she was open to it (at least in part) because she'd never tried it, never heard of it being a kind of sexual play, and hadn't had any bad experiences as a child with an uncomfortable enema, etc. In fact, she couldn't remember ever having been given an enema.
I've said this elsewhere in this forum, but it's up to you to make the introduction as pleasurable as possible. If you are wanting your partner to try receiving, don't expect the sensation of the enema to arouse them as it does you. They should be in a very high state of arousal through foreplay and even intercourse before you slide the nozzle in. My wife recounts that I "had her cumming so hard I could have hit her over the head with my shoe and she would have enjoyed it". So, you get the point. Make the enema an addendum to lots of great sensations.
If you'd like to be administered to, unless something is amiss, you partner is most gratified by pleasing you. Help them to understand what it is that you enjoy about the experience, make the first time as easy for them as possible, and be vocal about your pleasure. They'll probably feel awkward with it at first, guide them gently, give them encouragement, and make them feel like they're naturals, you've never had such an incredible experience as they provided. Then demonstrate that by pleasing them in all the ways you know they like to be pleased. Reinforce every positive aspect of the experience you can identify. We're all encouraged by success and praise.
There are so many variables that are to do with our individual makeup. Is your partner sexually adventuresome, or inhibited? I've had sex partners in my life who were thrilled at the idea of a new form of erotic experience they'd never tried, and I've had partners who thought they were really hanging it out there by giving oral. Certainly being anal-erotic is a huge plus, but even if they're not, a properly administered enema can be a very gentle source of stimulation. Is your partner bathroom-shy? We're taught to be very private in that regard, and women, especially, seek privacy. They, after all, actually have doors on the stalls in their restrooms, LOL. Men are used to peeing in a trough, unfortunately. Do your best to allow your partner to maintain their dignity, not be embarrassed. "Normalize" the experience as much as possible, try to anticipate your partner's comfort level and cater to it.
In regard to the men in this thread who complain that over the years their wives began to demure from enemas and moreover, their sex lives have diminished, two thoughts. One, I've found that most of the tribulations in my long marriage were caused by me, or, at least, poor communication on my part. Look inward. We men tend to see sex as an activity unto itself, unrelated to all of the other interactions we have with our partner. It's just the opposite for women, commonly. How you relate to one another, their perception of your feelings for them and how you make them feel about themselves has everything to do with their sexual relationship with you. Secondly, remember that our hormonal and general health changes/declines as we age. Could that be at the center of the problem?
The thought I'd leave you with is that deception is a relationship-killer. Be honest. But have some smart about you... make a good case for it, don't blurt it out like some kind of confession, make it as appealing as you can conjure. Good luck...