I'd say your partner is safe. Assuming he/she leaves SEA relatively on-time, the pilots can make up a lot of time in the air and he/she should definitely be into HNL on-time. HNL airport isn't that bad and can definitely be walked pretty quickly.

Hawaiian Airlines is the best when it comes to staying on schedule, so assuming DL can get him/her there with 20-30 minutes to make the next flight, they should be good to go.