There are dangers in writing about anything. There's the danger of getting it wrong, of not being honest and true to your material. In Matrimony, one of the things I had to be careful about, certainly in terms of the sections about writing, was not writing too close to my own experience. You don't want the work to become internal and self-referential.
Every writer is faced with the same question: do you write about what you know or what you don't know? Some of my writing students, particularly my undergraduates, err to one extreme or the other. They write simply what they know, which is a transcript of Friday night's keg party, or simply what they don't know, which is Martians. What they need to do—and here I'm quoting a former writing teacher of mine—is write what they know about what they don't know or what they don't know about what they know. In other words, they want the advantages of both closeness and distance.
If you're too close to your material, you're likely to be overly concerned about actual truth when fiction is about trying to get at a deeper truth through the imagination. On the other hand, you don't want to be so distant from your subject matter that the work has no heart. I tell my students that if they don't care about their characters, how can they expect their readers to care about them? I'm not saying they have to like their characters; caring about your characters is something entirely different. In the end, the key is to be as direct and as emotionally honest as possible.
My graduate students, many of whom are quite talented, are for the most part so afraid of being over the top that they're subtle to the point of obfuscation. They think they're being subtle, but the reader has no idea what they're talking about. I believe writers should risk being over the top. Charles Baxter says something similar in his wonderful book of essays Burning Down the House. You don't want to descend into sentimentality, but it's worse, I would argue, if your work lacks sentiment. And in order to get sentiment, you have to risk sentimentality. I tell my students not to be so afraid of being cheesy. They can always revise. That's the great thing about being a fiction writer. You can keep on revising until you get it right.