Does the ability come from reading fiction?
We both have online businesses, where we need to learn about marketing/tools/etc We both read lots of books (classic, non-fiction, etc) We watch TV shows, movies We do some sports
There is always something to talk about, when we just wander around a lake we will talk about more contemplative stuff.
When we eat around the house, we will talk about the quick wins we are having, countries we want to go next, making plans for the week, the new TV show we should start, what kind of music we want to listen throughout the afternoon.
If you are a stale unadventurous person, not willing to try new things, you'll sooner or later run out of things to talk about.
And you need to have independent lives to some extent. Don't try to do everything together. Spend some time apart doing interesting new things.