Bettas will surely drive you to the brinks of insanity, or beyond ;). Why they do the things they do, I do not know. Here are a few things you can do to ease your pain (and maybe save the day)

The good news is: Your betta flares, so he is interested in the female. Other good news: Sometimes bettas do spawn WITHOUT a bubble nest. Eggs seem to float miraculously on the surface and oftentimes will not sink. Can be a bit of a hassle once the eggs hatch cause you have fries EVERYWHERE but in the (absence of) nest. Again that is when stealing another male's nest could save the day. Still most of the fry will find a place to "hang out", usually alongside the tank's wall, where the surface tension is less. 

So do not give up, and if I were you I would leave him in there for a good week with or without a bubble nest, before throwing the towel. Goodluck, and if all else fails, remember you still have the dishwashing liquid option and daily morning exercises (JUST KIDDING!!!!!). ;).

Note: getting dishwashing liquid anywhere near a betta will kill him. So learn to tell my silly jokes apart from my sound advice, ok?

Q: Hi! I have started to try breeding bettas, but I'm having a little problem. I looked at the section on how to breed and took a male and female and put them side by side, everything went perfect! But for some reason when I put them in the tank, the male won't make a bubble nest, he just keeps flaring. Please help! Question submitted by Lance, Newport News - Virginia
A: Well I guess we are just going to have to teach you how to blow a nest on his behalf LOL. It's all in the mouth ;), we will start by a series of daily exercises where you will say "O" repeatedly for about 2 hours every morning (preferably on an empty stomach), while drinking small quantities of dishwashing liquid. The results will astound you (and your local hospital) . That's just the problem, isn't it, that WE cannot blow the darn bubble nest ourselves! We have to rely on HIM. Mr. Betta, the bubble blower Master. And as we all know by now, Mr. Betta has a mind of his own. So what is one to do when his betta 'blows' (as in does not want to blow LOL). Let us look at a few scenarios of our brand new soap (pun intended ) opera "Good bettas gone bad" (or should we call it "Blown with the wind"?).	scenario 1: The betta never blew a bubble nest and never will. Could indicate lack of health, or maybe lack of gland secretions to make the bubbles with.
scenario 2: Mr. Betta starts building an elaborate bubble nest for his damsel, but quickly become distracted by the Lakers game playing on your TV in the background. He suddenly longs for a night out with his buddies and some cool brewskies. Lets the nest go to hell and loses the damsel's good favors in the process (hum hum). Morality of this episode? When you have the attention and good favors of a damsel, do not snooze on the job ;).
scenario 3: Mr. Betta fantasizes of his future spawning exploits and blows huge nests in his jar. Once in the presence of the opposite sex however, he becomes stage fright stricken and will not blow a single bubble. Frustrated, you put him back in his jar, only to find the very next morning a Master Piece of a bubble nest gloriously making his jar look like a fresh brewskie (and the Lakers game is just about to start LOL). Makes you want to drink him down, doesn't it?
quit the hobby (hahahaha as if!)
try several males until you find one that will (hopefully) be up to the task at hand. (do I hear the ladies say "Amen"? LOL)
focus on bettas that appear to blow nests in their jars (unless scenario 3 applies, in which case you are SOL)
steal another betta's nest and place it in the spawning tank as a hint ("HelloooOooo! You are supposed to blow bubbles here!"). This can be achieved with a clean plastic spoon and a little patience. You'd be surprised how sturdy those little bubbles are. Most will stick together and nest can be moved that way. Careful when placing them in the new spot, that's when they might break apart, so ease that spoon into the water and then remove it from underneath. This trick has oftentimes worked for me.
add a floating thing under the cup (tiny piece of plastic wrap, piece of leave (plastic plant OK). Floating things inspire male bettas to do architectural creations (it's their artistic side kicking in).
make sure the surface of the water is not disturbed. If your filter is blowing too much air, disturbing the surface, the male will not blow.