Sex with your partner has gone totally of the boil. YOu have done as much as you can... weekends away, telling them how much you love them, buying them fun/sexy underwear, etc, etc.. you all know the drift. After all this you are still not getting any where. At what point do you consider that you have tried your hardest and sex else where can no longer be ignored. Tricky one to consider I know but let's see what other people think. Please state if you are female or male before u answer.
Another strike against monogamy. Suggest an open relationship if you're not content with the current situation.
Never. You should divorce, masturbate, or keep working at it. Since she's a cheating whore, I recommend the other two. If you find yourself a good lawyer, with a good PI. He will probably catch her; and she will lose credibility, which will help you in keeping the fair share of the pile. If you start cheating; she could catch you and that would give her leverage. She already has her gender going for her. Do not give her more leverage.
God forbid people should start doing that before all the unwanted babies, legal trouble, financial ruination, and cheating.
sounds like she's already getting it from somewhere else and has lost interest in having sex with you. cut you losses and move on.
If there are problems in the bedroom, there are often problems outside of it. If you think you have tried everything, make sure to consider the overall state of your relationship and not just your sex life. If it is over, it's over. You could suggest an open relationship, but realize that many fail because the relationship wasn't strong enough to handle it. Step back and take a long hard look at your entire relationship, talk to your partner and figure out what went wrong. Then you can either work together to fix things (you can't do it alone) or agree that your relationship has run its course and it is time to move on.