EDIT: As there is a specific part to the question, but the answer I already typed may be of value still I will address the specific issue as briefly as possible.
In this particular instance if you have one viewpoint it sets you up to tell a story where the other character becomes seen as an object of suspicion and some fear that mirrors some underlying fear in the protagonist. The clearest example of such a thing, bearing in mind that I have only seen the movie, is the original Twilight where the vamp dude is clearly supposed to represent this dark and deadly unknown that the heroine yearns for but fears.
If you go for two viewpoints and make them both the main protagonists then you are stepping into an area of a more distanced consideration of the mechanics of trust and distrust. If you are inside both of the main character's heads then the audience is placed "above" the characters in terms of what they know, this causes problems if you want to communicate that they distrust each other as the reader may tend to groan as they wonder why these two lunkheaded morons don't just talk to one another. That's not inevitable, but it is a risk.
Now, just to throw a little of a cat into these viewpoint pigeons. If you go for multiple viewpoints but you make those viewpoints the two main character's sidekicks that gives you two things you don't get otherwise. The sidekicks are free to not know what's really going on with their best friend, they can truly hate and utterly distrust the "other side" and you can much more easily create a scenario where no-one except two characters whose worlds you never see really know who can trust whom. You can also put all the "anti-other" propaganda in the mouths of your viewpoint characters. Obviously there are multiple downsides to this compromise but it is an option.
The best way to produce a "traditional" romance feel is to go with the single viewpoint but you have to realise that you are fated to make "the other" seem rather one sidedly always the shady one until the denouement. The "sidekick" suggestion allows both of our romancers to be equally "nice" and equally "nasty" but is a bit of a left field move in terms of narrative structuring.
ORIGINAL: This answer contains spoilers for The Shining -- You have been warned.
Single POV's clear advantage over multiple is the ease with which people will accept a story in either of the most popular voices first-person and third-person. The contrast between those has been discussed exhaustively elsewhere.
Multiple POV does tend to favour multiple third person narrative strands, to have multiple first person strands would usually be made more accessible with the use of a framing device e.g. an epistolary novel or some convention that told readers who's head they are in clearly at any given time.
One of the major joys of multiple POV is the ability to have a "villain" track in which you can put the point of view of an odious and detestable character in the narrative. Stephen King takes full advantage of this feature of multiple POV often, usually before dispatching these pariahs with the monster du jour.
Different numbers of POVs do actually seem to "suit" various genres to differing degrees. Here's a quick breakdown:
High Fantasy: One of the few that can get away with an omniscient narrator from time to time. Usually broad fantasy favours multiple, epic, viewpoints. Single viewpoints in fantasy e.g. Conan, tend to have a "grittier" edge. Often "Hero Chronicles" have a first-person narrator, who narrates the hero's life and deeds and occasionally adds their own piquant footnotes to proceedings.
Historical: Again, multiple viewpoints give an epic sweep. Also stepping through multiple viewpoints can seem to give a feeling of being less biased (even though this is nonsense) as the author can appear to be viewing a historical era from a number of different perspectives within one narrative.
Horror: Uses multiple viewpoints in order to allow the author to lead a character so deep into the darkness they never emerge again. Horrors with many multiple viewpoints but relatively few deaths can make really important characters ultimately disposal. A masterful usage of this technique is in The Shining where the summer caretaker, a kindly old man, gets brutally murdered by Jack Torrance towards the end after the audience has had a good long time to get to know him thus making the murder more effective.
Thriller: When a thriller employs multiple viewpoints it tends to have an epic/history-in-the-making/ripped-from-the-headlines feel. It seeks to dwarf individual participants in the circumstances that surround them. The more traditional thriller takes a much more limited point of view, in a pulpy environment it may even slide into first-person for the reason that the protagonist in a thriller where they are the centre of attention is often, on some level, "the patsy" i.e. Jason Bourne is very much the CIA's patsy in that series. Limiting the POV in this kind of thriller allows for the setup and execution of tortuous pot-boiler twists that the audience of such fiction loves.
Chick-Lit: Tends to stick to one or two POVs, part of the idea of chick lit is for the reader to emotionally engage with the character(s) in a very real sense, as if they were actual people instead of fictional, this is best achieved when the character can be some how set up to appear deep and nuanced while at the same time being every day and ordinary. The predecessors to the Chick Lit of the current day, the "Aga Saga" and the "Bonk Buster" were far more liberal and epic in their use of multiple POVs reading like historical or modern day soap operas.
SF: As soon as speculative fiction limits its viewpoint it tends to go existential very quickly indeed. Speculative fiction requires that we view the sciencey parts of the narrative through multiple eyes. Weirdly some SF, particularly so-called "hard" SF is meant to be on some level analytical and entertaining and interesting on an almost non-fictional basis as it treats its extrapolation as fact. SF novels of the "golden age" are often criticised for having terrible cardboardy characters but, in fact, the characters are not the point of such fiction, it's a fiction of pure ideation and the characters, to a certain extent, get away with being less than realistic for this reason. More limited viewpoint SF, think Philip K Dick, is all about the internal landscape alienated or made strange through interaction with technology, this is also a common theme in Cyberpunk.
So, to summarise, the more POVs you have the more "epic" your story will tend to seem. The multiple POV structure also gives you access to things like disposable one-shot characters, a certain latitude for narrative digression and other goodies that could risk your piece dissolving into a mess of self-indulgent tripe. The fewer viewpoints you employ the less this latter is a problem but the closer you come to the all important single viewpoint.
Single viewpoint is comfortable with first or third person viewpoints. It allows you to really push a character on the readership, risking of course that the reader may not like your protagonist or get bored with them. The self-indulgence risk here is that you find a voice for a first-person piece that you love to write in and everyone else hates to read. The more rigorous and disciplined you are the harder it becomes to deliver every single solitary relevant piece of story information on time and at just the right pace. You have to avoid confusing readers by not being able to tell them something vital. You also have to avoid allowing readers to see too much of the "wiring under the board" and leave them with a feeling that all the events that occurred did so in a manner that was just too convenient; this may be why many first-person detectives get seven bells knocked out of them throughout their every adventure.
HTH
