Is it permissible to lie to one's family and tell them that the suitor proposed through a female friend, in order to avoid their rejection due to having met him through a young man?

Lying is forbidden and a major sin. It is not permissible except out of a sharia-sanctioned necessity or a need closely approximating it. One can inform a close friend so that she may inform the family, or the suitor can find a suitable means. The importance of istishara (consultation) and istikhara (seeking guidance from Allah) in marriage should be emphasized.