Sad as it may be, sometimes beer lovers are paired with signifacnt others who have no appreciation for the drink whatsoever. Your wife or girlfriend may be a fuzzy navel-quaffing sweet freak who never took the time to tune her taste buds to the malt and hops channel. Your husband may have been a Coors Light man since his frat party days. Either way, an inability to understand a partner's passion for good beer places unecessary stress on any relationship.
Fortunately,given that there are so many styles, flavors, and characteristics of beer, there's probably one out there that your partner will enjoy; he or she simply doesn't know it yet. As long as they taste with an open mind, they are likely to discover tastes and aromas they've never before associated with beer.
So what do you serve them? A great place to find out is the Beer Advocate forum, where knowledgeable homebrewers and beer lovers have been hashing this question around for a while. To paraphrase their advice:
If your partner likes sweet drinks, start them off with a Lambic, like Lindemann's Framboise. It's a dry, light fizzy belgian flavored with raspberry, and chicks go apeshit for it. It's even pink!
If he or she only drinks American macrobrews, ease them in with Newcastle Brown. Newkie is a mellow, balanced ale, the archetype of the brown ale style. There's no super hop-bitterness or pronounced malt sweetness, so taste acclimation is quick and easy. After a few weeks of drinking Newcastle, they'll be wondering what else the beer world has to offer, and the two of you can enjoy long, fruitful tastings together.