I did the LDR for 2.5 years with a guy in east bay. SEA to OAK. I often flew down friday night and came back monday morning, about a 2 hour flight each way.
Here is what I found:
* if there is a company that flies the route direct, get on their mailing list. Sometimes they have discounts (sometimes involving booking directly on their site with codes).
* be flexible with your departure time. I often found that flying at 6pm was $60+ more than the 9pm friday flight...missing 3 hours with the sweetie wasn't worth the extra cost. You may find even more savings if you can fly on Tuesdays or Wednesdays.
* forget about flying on holiday weekends or be willing to pay. Expect tickets to be at least $100+ more than a normal weekend. Holidays include some of the lesser ones like Veterans, MLK, etc.
* Just look for sales and if you see a cheap price, snap them up. I flew RT for as low as $100 and skipped weekends if it was more than $200. Average prices were around $130. This was during the recession.
* Ultimately we broke up. I had a good time visiting him in California. Most of our weekends were like mini vacations - we saw so much of the area.