I would also recommend the Tissot Gentleman (automatic) if it is within your budget.
https://www.tissotwatches.com/en-en/t1274071605100.html
I presume this will be your partner's first "serious" watch, so something he can dress up or down definitely is desired (something that the Tissot Gentleman can do esp. on a black leather strap).
If you want to stick to Seikoland the Presage series is also worth checking, albeit more expensive than the Seiko 5 sports.
https://www.seikowatches.com/sg-en/products/presage/srp837j1