hmm... settling in to the relationship? How many months is "several"? I know I went through a period where I really wasn't feeling as interested in my now-wife as I had when we started. It's natural. You're not going to maintain the immediate passion of a relationship forever (imagine if you could, I thought about it and realized I'd probably be the most unproductive person in the world).
Now's the time to figure out if she really does have everything you want, or if it was just the physical. Find other things to do together, start a new hobby together, or spend more time apart. Have you talked to her about this? I know it seems like mentioning that would be the start of a fight, but she should know how you're feeling about it too. Maybe she's wondering the same thing.