[Grotesque]

Oh man, Iv heard this one before. Although, in your situation you have indeed waiting a long time. Crazy stuff. I might have an answer for you but its rather different and something I have done before but only once. It did work. If this doesn't work then Im out of ideas.

1. I wouldn't talk about the situation. I would act like its the last thing from my mind.
-- If she brings up a conversation about "sorry Im like this" or "I really want to but.." then change subject as quick as you can and if possible, something interesting or fun. A kiss and a tickle worked for me.

2. Try to make her feel great about herself. The better you can do this the more she will wont you. The aim is to make her guilt free and want your body without the thought they she HAS to do it. She must want to do it in a lustful way.
-- Get her some clothing that you feel she looks sexy in. Even if she won't wear it outside, make her wear it indoors.
-- Tell her she looks great and look at her body when you say this.
-- Flirt. I remember smacking my girlfriends bum when she least expected it and saying "wasn't me sweet cheeks". Its fun and unexpected.
-- Be naughty. If you go cloths shopping and she is trying some cloths on. Jump in with her and watch her change. Watch her change at home. Some girls might not like this but mine always had a big smile on her face when I did this.
-- Sarcasm. Im really bad with this (in a good way). If my girl says "Do these pants make me look fat" Ill reply with "Oh wow, you look HUGE"!! Usually gets me a slap but in a fun way. Either that or I will say "let me check.." and spend a good 10 sec feeling her ass. Always brings a smile.

3. The talk.
-- If you MUST talk about this sex situation between you both then be casual about it, not serious, stressed or angry. This will make the situation worse. Instead talk about how her head will explode when she orgasms or talk about all the great positions you both will get up too. Do it with a smile and a joke. Make it sound fun, not like its some sort of expectation.

4. Result.
-- With a guilt free atmosphere and lustful appetite she will want you no matter what. To want sex because she is horny, not because she feels guilty.