To give a false or misleading appearance to; conceal the truth or the real nature of:
to dissemble one's incompetence in business. To conceal/lie and hide one's true motives, thoughts, actions, etc., by some pretense; speak or act hypocritically.
Even though Beth knew she was madly in love with David, she still felt she had to dissemble (Lie & Hide) her true feelings to avoid being hurt by him, if he didn't feel the same.