RebbYidd23- that’s not so logical, since the girl is the one who needs the services of the shadchan, not the other way around.
I personally am not willing to pay a shadchan until a shidduch goes through… or maybe, maybe if it was a serious shidduch that didn’t end up working out. Maybe you can say it’s not unreasonable to pay a shadchan, but I don’t think it’s unreasonable not to want to do so, either.
I even met with a shadchan who told me that when she was in shidduchim, if a shidduch was a good idea but didn’t work out in the end, she bought a present for the shadchan. To me, that seems like more than adequate and a nice thing to do.