It's not my place to "decide" this for my partner. I've told him what I would do in the situation (there is other information, which I won't share, which makes it very clear that the bride doesn't want him there) but at the end of the day this is his friend and it's his decision.

Thanks to the groom's sister we have actual times now, so we're able to organise times for phone calls, which is all I wanted to begin with.

Partner is still feeling very left out and I've encouraged him to talk to his friend about it, but I can't do more than that.