Sex and Fighting

For the past few months, my wife and I have been fighting. We continue to work on things to make ourselves better in our marriage. Sex has been completely cut off. Not because of me. I mention wanting to have sex, and she says, "we are not good, don't fool yourself. If I have sex with you, it will be giving in to your selfish needs/wants. " We have 3 kids all ages 3-10. i have made sure that I am helping around the house, rubbing her back, talking to her, etc. When it comes to anything to me, I am cut off completely. I am fed up with no sex. Is it wrong of me to continue to want to have sex even though we might not be on the best of terms but continually to work on things?