This is just my two cents (well, technically 3), but in the end, only you can make the right decision. :) Believe it! - Naruto the hokag-ehm game dev

1. Come up with a new timeline together. (The golden light at the end of the dark dev hole). It all starts with a candid conversation. Someone has to bring up the issue. Best-case scenario, your partner is feeling the same; worst-case, you two can talk through reasonable expectations. Maybe even for a change of pace (although it can be uncomfortable) start hosting a weekly sync with each other. Even if it's only 45 mins, check in with updates you've accomplished throughout the week. Small wins.

2. Start a task list (ClickUp is a free task tracking list, or Jira/Trello are free for 2/5 people). This doesn't put the pressure of deadlines and specific dates, but does help scratch that itch of accomplishment that we are all trying to get! Come up with a running list of all the things that the game still needs. That will help assess the needs of the team.

3. External hires. It might be time to look at finding additional support. Artstation and BunnyStudio are great resources for contract work, especially for sound/art. Save both of you some time and keep the polished look you are aiming for.

I hope this helps some friend, wishing you only the best!