Thank you all for your stories/info.
I am warry of just joining a dating site because there are not only so many, but so many fake ones too.
You need to use your common sense and discretion when using a dating site. Sure, there are scammers out there. Personally, in all the years I used dating sites, I never met a scammer. But maybe that's because I am a woman who was mostly seeking men. I have met plenty of men who said they want love and a LTR but really only wanted one night of sex, though.
One person once told me to go to LGBT events, meetups etc. and that I might find someone there too, but I don't think there are any in my town/city.
So you're bi? I don't know how big your city is or where you live, but there are plenty of queers in most bigger cities. Or you may need to travel a bit, if necessary. Gay clubs have been closing since gays are more accepted at neighborhood bars and clubs nowadays. So it's possible you could meet someone (of any gender) at any neighborhood pub, especially if you go without your wife, especially if you go regularly. The key is to present as available and not just show up as a partnered unit.
The wife and I have just started to search for a possible second or third woman for us. She might not be as into the sex part, but the companionship. I'm for all of it ^_^
(Your wife needs a nickname. "The wife" sounds so possessive.) She needs to get her own partners and you get your own partners. There are so very few women out there willing to seriously date a couple, and then, if you do find one, she is likely to prefer one of you over the other, which will cause envy and all kinds of trouble. If your wife just wants a new friend, this might be what we call kitchen table poly, where your partner is friends with her metamour (your other partner). There is no guarantee and really no need for your partners to become close friends though. However, some people insist on this and will only date someone who wants to come to their house and hang out with their nesting partner on a regular basis.
That's not my jam but our member Bluebird (check her blog) always seems to bring her newest dating prospects over to her house to meet her nesting partners (husband and boyfriend) on the 2nd date! That's happening in her life right now.
Anyway, what about things to avoid? Are there any things that are a trap a new person might not see?
We've covered a big one, about not being unicorn hunters. Another "trap", or cringey thing, is sharing TMI about your sex life with the new person with your nesting partner. Another mistake is getting swamped in infatuation (new relationship energy, NRE) and talking too much in general about your new crush, or spending way too much time texting/phoning them, or insisting on rapidly increasing the amount of days per week you see the new person, or stopping dating your nesting partner altogether, or having sex with them, and devoting all your time and energy to the new and shiny person.
NRE generally lasts 6-18 months. It's intoxicating and you can become obsessive, but it's absolutely necessary to keep it in check, or your original relationship can suffer and even fall apart.