Dreams involving complex relationships can often reflect your subconscious feelings and dynamics in your waking life. In this dream, dating your friend’s mother who resembles your wife might indicate a blending of your current relationships or a desire for deeper connections with those around you.

Feeding her cake could symbolize nurturing or providing care, suggesting that you may have a strong desire to take care of those you love. The setting of a restaurant often represents social interactions and shared experiences, which may hint at your feelings about social acceptance or your role in your relationships.

Your friend’s jealousy might represent your awareness of competition or rivalry in your waking life, whether it's in romantic pursuits or friendships. It could also reflect your concern about how your relationships affect others or your desire to maintain harmony among friends.

Overall, this dream could be prompting you to examine your feelings about love, care, and the dynamics between those close to you. Consider how these elements play out in your waking life and whether there are any underlying emotions or situations that need your attention.