I think you need to move on. You have grown bored in the relationship and it has not moved to the next level. Time to find someone who can make you feel in love for the rest of your life!
OHHHH, Now I see why he is watching porn so often ;-)
OK, girls, please allow me to shime in. Yes, being tired can get anyone of the mood to get in the sack but please keep in mind that SEX is the best way to relieve stress, and humans need it. Like Magdelenna Said, you need to call off and get off.
This behavior is a vicious circle and it needs to STOP. Check it out.
If you are not horny, you wont want to have sex, if you wont want to have sex you will turn your BF down as soon as he tries, if you turn him down too much he will give up trying, if he does not try he wont make you horny, if you are not horny you wont want to have sex... Do you see where I am going here? The fact is that you have to sometimes suck it up and just let him do things and see where it goes. You are living together, if you deny sex, he is going to start looking at porn (like he already is according to your other post), cheat, and possible leave. Do not think that sex drives men but men need sex no less than woman need emotional support.
I used to date this one girl and every time I tried to kiss her while we where in bed she will stop me because she was not in the mood. One day I had enough and ignored her request to stop, I kept kissing her and tickling her. Soon she started laughing and all of the sudden she is on top of me ridding my like a rodeo bull. See, she was not in the mood at the beginning but she was not allowing herself to let me take her into the mood. After we where done, she was sitting there waiting for me to recoup to go for the second round. We didn't go to church the next day and spend the entire Sunday in the bedroom. I wanted to stop at points but she was possessed. After that, she never say no to me again. One day she was so tired that we agreed to go to sleep but set the alarm for an hour earlier the next day and go at it.
Perhaps, this is why he has turned to porn.
How long have you been on this peticular birth control? If your lack of desire matches of with the length of time you have been on this birth control then you may want to have the doctor prescribe you something new. If not, I would still see your doctor, he/she may have a better understanding of what is going on and may be able to tell you what you can do about it.