Other half not invited

I (31m) have been with my girlfriend (29f) for a little over a year. My friend and his partner have had to adjust their wedding plans due to costs etc and cannot accommodate for my other half as I can only assume they don’t know her (not met due to Covid/lockdown and would rather give that place to someone close but they would love for her to come to the after party.

How do I break this to my other half that she’s not invited to the day with me but can come to the evening?