Fluid bonding is... sticky...
Yeah, OK, pun intended.
Seriously, after having had a quad blow up big time due to the failure of one partner to disclose up front that she planned to have unprotected sex with a new partner right off the bat... And after having had my own husband (at the time) not want to start using condoms with that girlfriend, even she demonstrated an unwillingness to give the quad enough information in a timely fashion so we each could make our own sexual health decisions...
...And after my last longtime poly boyfriend and I surreptitiously had unprotected intercourse a couple of times, at his request and in violation of his agreement with his wife (with whom he was fluid bonded), and me feeling really shitty about that afterward...
I've personally come to the decision that fluid bonding is vastly overrated.
Seriously, if you think about it and experiment, it's almost always possible to find ways to enjoy sex and feel emotionally close to a partner in ways that do not involve fluid bonding. Personally, I greatly enjoy safer sex, it doesn't diminish my physical or emotional experience in the slightest. And for men who don't enjoy wearing condoms, I'm quite comfortable using a female condom.
Really: Not positioning safer sex as an obstacle, and knowing lots of options for it, is part of Being A Grownup 101.
Therefore, I chosen not to have unprotected penetrative sex with anyone, ever -- with the exception of some manual and oral stimulation, and then only after we've established trust through safer sex and had a clear discussion about our respective risk factors, boundaries, preferences, etc.
In my experience, the relationship pitfall about fluid bonding is not whether people do it well or consistently -- but that people often fail to communicate about it clearly and promptly. Especially if fluid bonding is an important symbol in your relationships.
Fluid bonding is often used as a stand-in symbol for many thorny issues: emotional investment, life commitment, relationship status, etc. It's rarely just about sensual pleasure or rationally considered health risks.
Personally, my own relationships are much less drama-prone (and, frankly, health risk prone) since I decided to take fluid bonding off the table for all my partners. I feel freer to say what's going on for me, voice my questions, insist upon clear answers, listen openly to what partners and metamours say, and flexibly negotiate options and solutions when issues arrive.
I understand that people who have a primary partner often consider fluid bonding an important part of their sexual connection. I'd ask you to consider in that case: What does fluid bonding really mean to you? Why do you want it? If it was a wiser choice to do without it (even with a spouse or long-term committed partner), could/would you do that and still keep your relationship healthy?