It's kinda sad that IUDs are almost unknown in the USA due to some bad ones ~40 years ago (1970s)
MrsTX got an IUD a year ago - cost us nothing out of pocket, and it works for 10 years. Effectiveness is about the same as a vasectomy. No pills to remember, no condoms, no hormones, no worries. Just some copper. Easily reversible - just have the doc pull it out. Heck, while it's not recommended, it looks pretty easy to do it yourself. You actually have to pay attention initially to make sure it isn't self-ejected - but that should be VERY noticeable, and a low likelihood.
I got pregnant with my paragard, which is why we ended up going with a vasectomy. Gotta be honest, after 2 pregnancies that ended in c -section, I didnt have a ton of sympathy for him. At least not physically speaking. I did understand that there is some emotional difficulty associated. His was free, courtesy of the navy.
Well, sorry to hear about that. Hope it worked out well.
Paragard is supposed to be 99.4% effective, so - 1 in 167 chance of pregnancy. Vasectomy is supposed to be 99.3% effective, so - 1 in 143 chance.
(of course, those numbers depend on which source you believe, but should be close.)
By contrast condoms are 82% to 98% effective, depending on "typical" to "perfect" use.
With any BC method, there will be pregnancies in a large enough population.