Plus ones for small ceremony?

Generally the wedding party is given a plus one even if they haven’t been dating for very long. However, if space truly is an issue you can use covid as an excuse.

It's your wedding, not his date night. If you can't accommodate then you can't accommodate.

Explain that you couldn't even invite someone you're actually close with, like another friend or relative and that a groomsman's girlfriend in no way takes precedence over them. If he still overreacts, then we know where he stands.

Definitely okay to say no to the plus one. 2 months isn't a long time and if you already had to downsize because of the pandemic why should their plus one be there instead of one of the guests you were going to initially invite before the downsize? I like Amelia's idea of offering to reassess closer to the date if there is room, but if there isn't don't feel bad. Not everyone can be included in a small wedding.

Your sticking to what you said and doing. Its a short dating period which you're not comfortable with the idea of having extras attending or knowing well enough. The groomsmen should have more common sense to understand where you stand in your decision.

No you’re not being harsh, especially with the pandemic going on.
We have people coming who are married but not their spouses. In order to keep things small, we had to pair back and people were pretty understanding. Stick to your guns; if he throws a tantrum, it says more about his decorum than yours.

We didn't do plus ones even for people who has been dating awhile but we have only met once. We have a small venue booked for family and close friends unless there married there probably not getting a plus one unless we are close with there bf/gf
We had sent out invites before covid and now have postponed till next summer (wedding was supposed to be July 18 had a secret immediate family only that day) most people didn't even ask if it was only addressed to them and the few friends that did double check weren't upset. I had two that weren't happy with it but oh well

It's your day and numbers are important if you don't feel you have space or want them I would stick to it.

I think you're right to stick to your guns. If they had been dating just shy of the 6 month mark I might be more lenient, but two months isn't a long time. If your wedding isn't for a while you could change your mind closer to the wedding if they're still together, maybe 3 or 4 months out if there is room ask if he still wants to bring them. I assume that you might have gotten to know their significant other by then and you might want them there more.