LB – I think we’re talking about real Gedolim here. I think that was bluhbluh’s point. And a Gadol Hador would be unlikely to tell someone this except in very specific cases.
It sounds like there are a lot of conditions to this issue. So unless you’ve listened to the entire shiur, I don’t think you should let it concern you.
I certainly don’t think you should listen to any Rabbi you know who tells you to marry someone specific, since I highly doubt that any of the Rabbis you know are qualified to do so.
If it does happen and you really are concerned, ask another Rav if you have to listen to the first Rav. And I am not talking about a LOR. I mean that you should ask someone much greater than that for such a serious issue. Personally, I would probably write to R’ Chaim Kanievsky and ask him. But if you’re not comfortable with that (and it might not be so appropriate for you to do so), you can email someone like Rav Leff. I actually think he might be a very good person for you to ask your questions to in general, both halachic and hashkafic.