Welp, they finally did it: The three previous installments of the glittering, love-declaring, torn-between-two-monster-lovers Twilight series have basically been one massive buildup to the moment when Edward gives Bella the vamp-boner, and today it finally happened. Luckily, that carnal union is sanctified by the Lord. Which is a little weird, given that vampires traditionally fall under the dominion of hell, spirituality-wise, but in this case it's cool, because Edward's coven only feasts on animal blood -- just one example of a saga that takes its phony morality very seriously putting in the effort to explain away the contradictions.
But first let's take a look at the hot, hot vampire secks we've all been waiting for (just skip right to 0:58), wherein Edward's pent-up ejaculation is so powerful he breaks the bed. Sexy? Yes, but it portends horrible things to come. Edward's immortal spunk, you see, creates a zygote that threatens to kill our ordinary human heroine. "The fetus is incompatible with your body," the ginger vampire helpfully explains. "It's too strong." It is, as Edward adds, crushing her from the inside out -- which is pretty hard to visualize if you think about it.
By most standards, the point at which a fetus threatens to crush the mother from the inside out would be an excellent time to consider an abortion, but we all know in the Twilight universe that would be out of the question. For in the Twilight universe, we adhere strictly to a fundamentally chaste set of family values that rule out abortion and premarital sex but apparently do not rule out toying with emotional infidelity by continuing to pine over a man not your spouse (see: The continued presence of Jacob). Instead, we solve the problem of the vampire fetus destroying its mother by turning the mother into a vampire -- a solution that may or may not make you wonder why they didn't get that inevitability out of the way before they got their coitus on, but whatever.
The trailer does contain one illuminating moment, however: There's a look Bella's dad briefly flashes at exactly 2:05 and about a half second. It's hard to define this look -- sadness? Horror? Resignation? Disgust? -- but it more or less sums up how we feel about this whole thing.