My wife would like to use the FMLA to enter counseling due to sexual harassment. Will this be covered under the FMLA law?

You don't provide enough information for me to give a definitive answer.  However, generally, where the employer is covered by FMLA, employees are entitled to up to 12 weeks unpaid leave to obtain treatment for a serious health condition.  If the counseling is treatment for a diagnosed serious physical or emotional condition you may be entitled to leave for the treatment.  If you are entitled to the leave, it may be taken as "intermittent leave" - used in hourly increments rather than entire days off.  However, if you are simply seeking counseling to help you resolve personal issues, that sort of intervention  may not be a "serious health condition" which would entitle you to leave.