My wife and I have been happily married for 14 years and have 3 wonderful children.  I adore her and we have a great union in most ways.  Our sex life has never been great and at times has been a source of great tensions between us.  This is the case again now.  Though we communicate well in all aspects there is great difficulty in discussing sex.  She seems to withdraw and I have elected not to raise issues any more. We have for years had an arrangement where we would have sex twice a week.  This arrangement was mutually agreed upon and she assures me it is fine.  The sex is very restrictive and she does not usually like to be touched by me much.  Throughout our marriage touching her sexually has felt unpleasant for her initially.  However sometimes if the moon align right and there is some persistance the unpleasant fealing dissipates and she can become aroused.  She can come to an orgasm quite easily and is clearly highly arroused.  She does seem to surpress expressing this though.  Is this a common phenomenon ?  Is there something that we can do about it.  I have difficulty raising this with her.  Also she is usually really ticklish in general.