I kind of disagree that captivity would make Orodreth less likely to be able to be married. I don't really know why it would. He might have something like depression, but still want to marry. He will have children in a later season.
And I want to caution again that he should escape, not be freed, because he shouldn't be under the Spell of Bottomless Dread.
Yes, I agree that regardless of what happens, Orodreth and his wife do have children at a later time. So, they are not estranged or anything like that. What I would find...a little difficult...to show, would be Orodreth resurfacing after his time in Angband, reconnecting with Meril (or meeting her?) and then being like, yep, everything's fine, we're getting married! I would expect a bit of a slower recuperation time in which he would build up to the point of being okay with marriage (and *especially* so if he's not already married). She'd have to get to know the 'new' him and decide if this alters her choice in any way. So, while I don't mind telling this story, I would caution us not to rush through this portion of it.
Gwindor presumably wants to get back to his beloved Finduilas after his escape from Angband...but...she cannot bring her heart to accept 'new' Gwindor. Showing Orodreth and Meril surmount that hurdle and remain (or become) a married couple would be good - but it isn't easy or automatic.
Human soldiers marrying before they go off to war (or during leave while they are temporarily home from war) is apparently not a thing elves do. Apparently, they would give themselves time to work through any issues rather than rush into marriage immediately.
So, once again, it becomes a question of timing. If they marry in peacetime, and then he is captured...they have all the time in the world to work through his issues after his return. If, on the other hand, he is made captive first, we'd need him to escape early enough that he comes back, has time to recuperate, and then build a romance with her/marry.....before Glaurung's appearance in Episode 13. It can be done, but we'd have to pay attention to the pacing to keep it from feeling rushed. There are large time skips in the latter half of the season. I'm not worried about him having time to heal. I'm worried about not giving the audience time to see this play out in a way that makes a wedding make sense.
So, Orodreth time constraints: Wedding some time in Season 4. Captivity sometime in Season 4. Release from captivity sometime before mid-Season 5. And the wedding can't occur while he's in captivity!
The 'did they escape or were they let go?' question is significant, but I don't think there's any reason to prevent Sauron from slipping a SoBD elf into a group of elves that he 'lets' escape, thus disguising his compromised spy among other escapees. And there can be a legitimate jail-break. I don't mind how we develop the story, but I don't think it's a case of *only* the SoBD elves being part of the 'catch-and-release' strategy. Sauron needs to come across as a master mind with a long term plan; the elves should be doing their best to get away.
And I agree that it's important that some elves die in captivity or stay captive indefinitely with no hope of escape. Angband is the Hells of Iron, and it should feel like a one-way entrance, not a revolving door.