<human>: The title says it all. I'm browsing Tinder, as you do, and I come across somebody with a lot of mutual Facebook friends, and it is definitely 100% without a doubt this guy I know who is engaged. We're in the same social group and hang out fairly regularly. Do I have an obligation to do anything in this situation? If so, who would I tell? Facts:

* I'm not really close to this dude, hence not being Facebook friends, and I've only met his fiancee a couple of times.
* They got engaged crazy fast, as in a couple of months after they started dating fast.
* The Tinder profile is a regular-seeming Tinder profile that doesn't say anything about "just here for friends" or whatever.
* I don't know whether they're in any kind of open relationship situation, but neither of them seem like the type and this group of friends isn't really the type in general.
* I don't know whether he matched me, I swiped that shit away. I kind of don't really want to know?

Give me a shortened version of the text
<bot>: A friend of mine showed up on Tinder. I know for a fact that he is engaged. Do I have an obligation to do anything?