It's like a honeymoon phase engagement on crack. I mean imagine dating Grace - free room and board, holidays every 2 weeks, absolutely limitless disposable income, puppies running around, invites to swanky events - it would be hard not to get swept up in it. But Jesus. It's not real life.
Have they been through anything difficult together to see how they'd cope? Have they seen each other on no sleep, grumpy, burnt out, lost in a foreign city, stressed about the future, grieving, having an *actual* work crisis, dealing with a mental health crisis, feeling ugly and unlovable, or questioning their direction in life - you know, shitty life things that all normal serious couples do come up against over time - and work through together and bond over and support each other with?
They've basically had an 11 month magic carpet ride.
ETA: Also the fact he's 37 and has (hopefully) been in other serious relationships and KNOWS this isn't normal but is locking her into it anyway is ick