In a weird way this storyline is really demonstrating that they're falling more and more in love each other...
Robert desperately trying to make Aaron happy, as reflected by organising an amazing surprise to such a level of detail that is beyond anything (I mean he even bought Liv a dress to wear when she was the croupier, and was so disappointed when she didn't wear it)!
For Aaron it's demonstrated by his insecurities spiralling more and more out of control, desperately trying to hold on to Robert because he thinks he's going to lose him to someone else...