I had a similar situation.
Just after I got engaged, I informally invited three of our secretaries at work to my wedding. Shortly afterwards, I went to work elsewhere within the same organisiation but still had some limited contact with these secretaries.
It was two years before we got married, by which time, I wished I had never invited them, as I no longer felt close to them. However, I wanted to keep my word, so I did invite them, minus their partners (they all work together and are good friends).
Unfortunately, I had invited eight of my therapist colleagues, and not wanting to appear to be treating the secretaries any differently from the therapists, I was forced to also invite them without their partners. To be honest, we were £555 better off for not inviting 11 partners, so when I look at it like that, it was a good move!
However, the crucial point was really that I knew the therapist's partners as friends and would have liked for them to be there really. In the event, everyone came and nothing was ever said. You can't please everyone, and why should you have a bunch of strangers sharing your most intimate day? I find that quite strange!