Because like Salt 'n' Peppa (and if you don't get that, look it up), I believe honesty in sexuality is key.
I've run into a lot of people on the web that say sex in a novel is "boring" or "unnecessary" in a novel. For me, one of the big benefits of fantasy is that we can include sexuality in our characters. I'm not talking about a one handed read for the sake of one.
Sex is an important human act. Don't put it in just to spice the book. Make it come straight from the characters and become part of their emotional landscape. A girl losing her virginity may very well be awkward and in pain, and not have much fun. She can also do it just to not be a virgin. People don't have to have good sex. They don't even have to have loving sex, or sex they are happy about later. Or maybe it is a beautiful moment that shows a progression in a loving relationship. At any rate, sex is a solid part of our identities. If you don't respect that, you aren't respecting your character's whole being.
That and it pisses me off that in my writing I can show someone getting their head blown off amidst shattering, bloody, wiggling goo, but if I show a blow job everyone freaks! That's a creepy flip about positive and negative.
The other great thing about fantasy is that it has a long history of being open about homosexuality. I grew up with gay and lesbian influences. I actually didn't understand that homophobia still really existed for years. I thought it was a joke. Homosexuality, from a major factor to a minor mention, makes it's way into every single one of my books. I didn't plan that way, but I believe gay, lesbian, and bisexual issues permeate our lives. Ignoring that would be like avoiding any other factor in my characters' lives, or my worlds. I do not believe that is a platform of any kind. I believe it is life.