I recently read an article - written a few years ago - which really bashed Trek's treatment of romantic/sexual relationships and basically said that none of the Trek shows ever managed to portray believable and interesting relationships, that their treatment of sex and romance is immature, and that most of the romantic pairings were mismatched or had no chemistry. (I think it said something like "When was the last time you could say a Trek couple lighted up the screen with their chemistry?") I remember that I agreed with some points in the article and disagreed with others and thought that it did point out some problems but it exaggerated it all.
What do you think? Was Trek ever good in portraying romance and/or sex? Did it have too much, or too little of it? What do you think gave been the examples of good, compelling and interesting portrayals of romance in Trek shows or movies, and what, OTOH, you really could have done without? What has been lacking? Which couples were really interesting and great to watch, which were mismatched and unbelievable, and which were just dull? Do you think that perhaps some of the 'pairings' (whether slash or hetero) that never actually became couples except in fanfics had more sexual chemistry than those that did?
For starters, I will say that I always despised the expendable love interest of the week routine that ruled in TOS, and occasionally persisted in the later series. Even though some of the storylines and episodes were great, on the whole it was boring because you always knew how it would end, that the love interest of the week would have to be gotten rid of and never be mentioned again. But I also thought that TNG came off a bit childish with playing up the eternal sexual tension between its regulars but never letting them get together (not before the finale or the movies, anyway). Both these things are the consequence of the unwritten rule that heroes can't settle down, or the inability of shows to handle the idea of the main characters having lasting relationships (by lasting I mean: longer than one episode). Which is a bit silly, really - it would be stupid to have everyone on the ship involved with each other, but it's equally unrealistic to make everyone single. DS9 did better by breaking those rules and letting the regulars actually have steady relationships, even which each other, (though we could discuss the merits of each specific pairing). I can't speak for Voyager, since I'm watching season 3 (but don't worry - I've already been spoiled, before I even started watching, on who gets together with whom, and who does not...) and I haven't watched ENT except for the pilot, so I can't comment on it either.
Two other things: I also think that Trek should have had a few homosexual relationships, but dealt with in a mature way, not as a silly Mirror Universe titillation.
And, I love the fact that Trek likes to feature unexpected pairings and interspecies relationships, and hybrid children - even if it doesn't make sense scientifically - since it is really a metaphor for interracial/crosscultural relationships, overcoming differences etc.
What I don't like, is the habit of introducing the pairings that are not just unusual, but very mismatched - due to one person being much more attractive than the other... and surprise, surprise, it's always the woman who is the more attractive (basically, just a variant of the "Ugly Got A Hot Wife" stereotype). It started with Rom and Leeta, but at least those two were of the similar intellectual level and interests. But the most jarring example is Neelix and Kes. Now, don't misunderstand, I'm not saying that it's all about physical attractiveness... it is also a matter of personality, charm, etc. We have to at least understand that those people see in each other, or in this case, what Kes sees in Neelix... and I am really not getting that from the show.