According to the Umami Information Center (yes there is one), Umami is defined as...
When humans eat, they use all of their senses (sight, hearing, smell, touch and taste) to form general judgments about their food, but it is taste that is the most influential in determining how delicious a food is. Conventionally, it has been thought that our sense of taste is comprised of four basic, or 'primary', tastes, which cannot be replicated by mixing together any of the other primaries: sweet, sour, salt and bitter. However, it is now known that there is actually the fifth primary taste: umami.
But what does this have to do with romance writing?
As the food definition describes, we look at food using all of our senses. As the definition also goes on to say, taste is broken down into 4 more categories. In fact, we can break down all of the other senses into small categories as well. Sight can be the exact thing we see as well as the perceived thing we see. Hearing involves tone, volume, pitch and so forth. I think you get the idea.
The element of umami was more of that unnamed sensation that somehow brings to life the food that the other elements don't quite describe. Because romance writing (and I guess you can include women's fiction into this argument) deals with relationships and human emotions we have to bring in something that extends beyond the simple five senses.
If we think about falling in love, we often cannot describe what we are feeling. According to an article from ABC News in 2009 by Sheryl Kingsberg, Ph.D. she notes that researchers show that there are brain changes that make falling in love a physiological change. She goes on to note that if we really want "understand what falling in love is -- the best concept to understand is the concept of limerance. Limerance is that period in a relationship of great passion, when we're almost obsessed with our partner, when we can think of nothing else..."
The point is there seems to be this "feeling" we have. How many times have we seen in movies when some kid is asking a mother "how do you know when you're in love?" What is the answer? "You just know."
I think, in all honesty, what romance authors are forgetting is that feeling they had when they were in love for the first time (or the second). Sure, we can write a scene that has "all of the elements of a great romance" but the passion and the emotion you felt is simply not there. That missing element, the umami so to speak, is what prevents the reader from truly getting connected with the characters and their situation.
When we talk about classic argumentation, one element that is often discussed is that of "ethos." This is not only the credibility of the speaker, but also the connection that speaker makes with the audience. You can use the same idea here when we talk about writing. For romance to really work, it isn't simply about putting words on a page and telling a story. It is about giving the reader the chance to fall into the story and feel the same things the character is feeling. If they hurt, we hurt.
As you sit down to write your romances, you need to take some time to really "REMEMBER" what it was to fall in love. Remember those giddy feelings you had when the whole world made sense and didn't make sense at the same time. Remember those feelings of not wanting to be away from that person. How everything you did during the day reminded you of the person who wasn't there.
By reintroducing those thoughts into your brain prior to writing, and while you write, you will find that emotion just coming across in the words. Remember, it isn't about using the right terminology. It is the feeling.