Girlfriend can't orgasm

Recently we haven't had much success in getting her to orgasm with oral sex. We used to be able to achieve multiple O's with gushing.

Now, I can go down on her for up to an hour and she'll not experience anything. The end result is increased frustration and soreness (and then obviously a lack of desire for future oral sex). In fact, if I can't get her to orgasm and get her comfortable first, then there will be no sex. Only once or twice in the 2 years that we have been together has she asked for sex after not being able to orgasm through oral (but I did give her a G spot orgasm on both occassions). It's a requirement for her to have an orgasm through oral before we have penetrative sex.

So the inability to give her an orgasm leaves her on edge and feeling uncomfortable.

My issue is that she doesn't enjoy foreplay. OK I'm a little quiet when it comes to flirtatious words etc. but I am big on the whole spending time to get each other worked up. She's extremely impatient. It's a case of: turn the lights off, get in position, get to work. I've tried to take time to kiss her etc but she gets angry and tells me to just start directly. Then she cannot work out why it doesn't always work and blames me for not introducing variety - I have tried movies, making noises, fantasies etc.

There are times when I can't seem to find the right spot - she expects me to get there immediately...if I can't get her to orgasm in a relatively short time, I'm subjected to her full blown anger - which inlcudes turning cold and forcefully pushing my head away from her (and calling me an idiot or stupid - completely ruining the situation). I just don't feel any passion!! It's a case for her of me just getting to work and then she'll turn it on me and say that I'm not doing it right or not making her feel turned on!

We haven't had sex in about a month (around 2 weeks not inc. the 2 weeks she's been away overseas). Right now I'm reaching the point where I really want sex - masturbation is not helping to curb my urges! She's back overseas for the next 5 days and I have no way to relieve this feeling - I don't want to cheat!!

In the past few days, I've failed in getting her to orgasm and the result was to have her insist on going for a ridiculous length of time until she is in pain. I am beginning to think that there is something seriously wrong with her state of mind.

As for spending time together, that's limited to whenever we are both at home. I come home from work most evenings around 9pm. She will sometimes stay out at her company until 10pm and go out with friends. We don't share much outside time together - most of it is at home watching movies etc. Every second week she is away for work overseas as an international guide. So as far as I'm concerned, we don't have the chance to go outside together and bond like normal couples do.

Despite that, she still acts loving (in between the nasty comments - blowing hot and cold) and talks about our marriage in December (and the migration from China to Australia - no, she's not using me for a green card!). Our marriage visa has been approved so that's going ahead as planned. She argues that we will have a lot more time to spend together after we move to Australia...

I just look around and realise that I'm on my own too much, cannot overcome this sex problem and that I feel put down too much! I will admit that I'm generally pretty easy-going but her foul tempers tend to really affect me.

I love this woman but I also crave a close intimacy that she's not providing when she's around - we can hug/kiss in bed and share mutual masturbation but I want sex and more foreplay. And more fun. She accuses me of being boring one minute, then comes to me and is all loving the next. I really need some advice on how to tackle this before we get married!