My sim is going for the Soulmate Aspiration, but is stuck on part 3 - the game doesn't seem to recognise her husband as her soulmate?

They both have full green + pink bars, and have been married awhile. I'm not really sure what more I can do for them!

Any help would be appreciated

Unfortunately, this is apparently a not-so-uncommon bug. The workaround I would suggest is in this thread (which also has quite a few people describing the same problem). That workaround is to use a cheat to autocomplete the milestone since you've done everything else already. The next step apparently requires you to do 50 interactions with the soulmate, so if it isn't registering then either, they suggest keeping track and then using the cheat again. The cheat is "aspirations.complete_current_milestone". I've had to do this with other aspirations that weren't registering correctly.

Here's a thread from the official help forums with a ton of people complaining about it. I didn't read that one all the way through. Here is another one about the final milestone for Soulmate. On page 2, a poster shared a different workaround that involves using cheats to 'remove' the relationship and then cheats to build it back up again. At least that poster and another person said that worked for them, so it's up to you to decide if that's acceptable and more or less work than keeping track of interactions.

Sorry it's glitching the aspiration. Good luck!

Oh okay - at least it's not just me! Looks like I'll be using the cheat to get round it.

Thanks for your help!