Sorry to say it all makes me suspicious - unless there are any witnesses who saw the whole chain of events as described.
Maybe the Sherriff’s office just doesn’t want to say anything until they’ve checked out his story, but I hope they’re doing do. First, do they know for certain she was even there? (something could have happened to her elsewhere and this could be a cover story). Did witnesses see her? And did anyone else see her go under? etc.
Sad to be suspicious of what may be just a tragic accident but this sounds rather weird.... and the whole thing about she was gone by the time he took off his jacket — that sounds very hard to believe. If you’re greatly concerned about someone swept away in the water you don’t take your eyes off them, certainly not for more than a couple of seconds.
You said — “Sorry to say it all makes me suspicious - unless there are any witnesses who saw the whole chain of events as described.”
It’s not suspicious to Oregonians who know the beach... LOL...
You keep your eyes open and it doesn’t take much to get knocked off your feet and then you’re in trouble, in a hurry...
And if you’re around rocks (which they were from the story), it’s easy to lose sight of someone and with the waves coming in, you can lose sight of the person in the troughs.
Personally, I would never go into the ocean to get someone. I’d call for help but that’s it for me. If I did, it would be the end of me, too...