Dreams like yours often reflect complex emotions and experiences related to relationships, connection, and personal struggles. Here are some possible interpretations of the elements in your dream:

1. Beautiful Life and Connection: The scene with Madeline, Ryan, and their baby represents a life filled with joy, love, and fulfillment. Your feelings of admiration for their happiness suggest a deep longing for connection and contentment in your own life. The absence of jealousy indicates that you are perhaps more at peace with their happiness than you have been in the past.
2. Fear of Ruin: Your apprehension about taking a bite of the cake and ruining it may symbolize your fears about disrupting something beautiful or precious in your life. This could relate to your own aspirations or relationships, where you might be worried about making a mistake or causing harm.
3. Chase Scene: The scary doctor chasing you and Stephen could represent external pressures or fears you are facing in your waking life. This might relate to anxiety or stressors that feel threatening, but the transition to observing the happy life inside indicates a desire to escape those pressures and seek comfort.
4. Ghostly Presence: Feeling like a ghost when you entered their home suggests a sense of detachment or a feeling of being an outsider in situations where you desire to belong. This may reflect feelings of isolation or a struggle to connect with others.
5. Physical Pain and Miscarriage: Waking up with stomach pain linked to your experience of miscarriage could indicate that the dream is processing feelings of loss or grief. Dreams can often manifest physical sensations that reflect emotional states, so it's possible that your body is responding to your feelings about your past experiences.

Overall, your dream seems to be a mixture of admiration, longing, and processing past experiences. It may be helpful to reflect on your current emotional state, your relationships, and any unresolved feelings regarding connection and loss. Consider talking to someone you trust about these feelings, as it may provide additional clarity and support.