Noa is a self-worth vacuum. Rihito deeply respects her for her professional skills, artistic sense, her giving nature, and impeccable work ethic, and he is honest to a fault. He is an infinite supply of the affirmation that Noa can't give herself but so desperately needs to be content. That's why she is constantly pulled towards him and will always try to be around him. It's basic physics.
The good news is that Rihito's respect for Noa isn't built on misconception. Every quality he respects Noa for is one that she actually possesses. No matter how much Noa fears that a day will come when Rihito understands the truth about her - that she is fundamentally unlovable - it simply won't. Because it's not true. And Rihito can easily spend their entire life together expressing his honest admiration of her. Lies are hard, telling the truth is not.
I'm not sure anything else is required for the relationship to work out long-term, at least on Noa's end. There isn't a boundary that Rihito is likely to set that she'll find unacceptable. (If anything, her past relationships have proved that she's far too accommodating, to the point of self-denial.)
What does Rihito get out of it, is the question. I think this chapter seems to try to show us that even though Rihito may not have much of a romantic or sexual drive and can be alone basically forever and be perfectly content, he does experience loneliness, and there'll be times when he needs someone else to be there for him - and if there's anything Noa will be all too happy to supply him with endless amounts of, it's herself.
Of course, as has been alluded to, if Rihito ever develops romantic and especially sexual desire towards Noa and she realizes, it'll be happily ever after, provided he lives through the initial onslaught of affection.