When did this become the norm in Ireland?

I have been invited to two weddings in Ireland this year, and both are two-day affairs. One of the weddings is of a very close friend, and while I am delighted to be joining him on the day, I am balking a bit at the prospect of the second day. I think one day's eating and drinking to excess will be plenty for me, and tbh I would rather avoid the extra hassle and expense of staying for a second night.
Is this likely to be seen as a sort of faux pas or snub? I will be coming back from abroad to attend the wedding, so I suppose that is in my favour; I would like to hear a few opinions from other people before letting them know that I will be attending the first day.