I just came on to post something very similar. I've seen a very different side to Arthur as time has gone on, culminating in his awful, insensitive words about Aoife today. I agree that it's him who put the pressure on for babies rather than Brian.
Aoife clearly adores Arthur. There are selfies going back 10 plus years on her insta with him - more so than with any other family member. She's infatuated with him and Arthur knows this and uses this to his advantage. He knows she probably would never dare say no to him. Even if she did offer to be their surrogate day one, you can be sure that idea was planted in her head by Arthur.
She's amazing and one of the family when growing his baby, but now Blu is here they are a 'family of four'. Recovering from major surgery is 'relaxing'
No mention of anyone waiting on Aoife. She's done her job so they've no need for her, currently (until Brian is back to work, or there's an event to go to). I'm sure they do love her but they've exploited her. Her father and sister must be so worried about what's next for Aoife.