It is quite common to see great fares from Colombo to various destinations with Etihad, Qatar Airways and Emirates, but this is better than most I have seen lately.
This is a screenshot of the price for 2 tickets (total price one way), as you can see it is 198000 LKR, which translates into 4993 dirhams for two people, or 2500 dirhams pr. person. The return is slightly cheaper, making the total price less than 5000 dirhams pr person. The catch is to get this price you must book 2 tickets, if you book only one it is about 4000 dirhams each way pr. person.
Also, to make it more exiting, Qatar airways is currently operating the Doha-Boston route with their brand new Airbus A350s, which in itself might almost be enough reason to buy a ticket.
Those tickets also earns you a nice amount of points, a round trip earns you just short of 22.000 miles, which is enough for a one-way upgrade between Doha and Colombo (for your positioning flight?)
This fare is good enough that I would go to Colombo in order to do this flight going to the US, especially if I had a travel companion to make the price that much lower!