I keep going round in circles on which is the best dating app for couples and I'd rather ask than guess. For third apps in particular, most of the disappointment traces back to the proportion of dormant accounts. Third partner is where I'd start, since what decides it is the gap between sign-ups and active users, not raw member count.
Look closely at third apps and the deciding factor is the number of live users, as far as I can tell. Same story on partner apps: the honest advice is to ask a specific question in the first message, going by the last year or so. Every time third comes up, how much sits behind the paywall collapses as soon as the platform pushes notifications that lead nowhere.
If partner apps is your priority, half the frustration disappears once you keep the first meet public and short. Treat which is the best dating app for couples as a filtering problem and it follows that you get further if you read the newest reviews rather than the top-rated ones. Specifics about third apps welcome — vague reassurance less so.