Just back with an update. My partner went to an appointment in London in mid May and was told that they will have to submit a waiver request to DHS. He had gotten into a fight when he was 19 (now 32). The assault charge was a crime involving moral turpitude so it had to go down waiver route. Additionally, my partner had overstayed his ESTA 3 years ago by 18 days so the officer said that it shows a pattern. My poor husband went with so much supporting documentation and the guy didn’t ask to see any of it haha not even 1 thing! Asked him a few questions but didn’t really care for details or ask specifically about ties to the UK…
Anyways, they said it could take 1-6 months to hear back about the waiver and they would be in touch via email. The interviewing officer said that he was optimistic given that it has been 13 years but that it could always go either way.
2 days ago he received an email requesting his passport be sent to them for visa issuance! Hopefully this brings some hope to others who may have similar situations. 🙂