Pretty much EVERY guy likes blowjobs and jerking off. It's kindof like professional sports,sports cars, beer... it's in our DNA.
When you are in a situation where your significant other (wife, girlfriend, ... whatever) isn't giving you sexually what you need you eventually will explore other options.
I have the same situation myself... My current girlfriend finds pretty much everything that guys find pleasurable (handjob, BJ, etc.) as gross. All she wants to do is for me to go down on her and then fuck so she can get off 3-4 times. After I get off, even once, she's done for the night.
A few nights ago I was super horny and kindof hinted that I wanted some. When I discovered she wasn't totally in the mood I casually asked if she wanted to give me a handjob... Her response, and I quote "You can do that yourself.... I'm tired."
If I'd give her an answer like that there would be hell to pay!
As a result I ended up placing an ad here on the site to see if another straight guy was in the same situation as me and would be interested in solving our problems ourselves. Basically trying and get each other off as many times as possible. We both have the same equipment and desires - know how everything works - so it simplifies the process.