If I may reply as a fellow traveler who has many friends in Ireland, I can share with you that there is a real concern regarding visitors from outside the country. I have friends who own a really lovely and successful B&B who will not be opening anytime soon due to their risk group (>70 years old) and also the fact that their daughter who helps out quite a lot has a 3-month old infant. This is not so much an issue of discrimination as it is personal concern, especially (I would think) if guests are quartered in the same dwelling as the hosts.
The cautious hostess may also be taking into consideration the international guests who have chosen to ignore the restrictions. I am embarrassed by the stories I read of Americans doing this.
At this point, I have doubts whether the 14-day quarantine will be lifted any time soon for American and UK travelers alike. Although I will be going to Ireland in August, I have booked a self-catering cottage where I will happily escape from the world for 7 days. I don't plan on visiting friends or going horseback riding as I do every year, and that's okay for me. But if your intent is to tour Ireland, which is what it sounds like if you are booking multiple accommodations, please reconsider another time when you can fully benefit from the lovely hospitality and amazing activities that Ireland has to offer.
With best regards!