Dreams about being invited to a party can symbolize a desire for social connection or a need to reconnect with your past. Since your old high school friends were involved, this could indicate nostalgia or unresolved feelings about that time in your life.

Being almost late in the dream may reflect feelings of anxiety or pressure in your waking life, particularly regarding social obligations or expectations. It might suggest a fear of missing out or not being able to meet the demands of your relationships.

Buying things at the grocery store may represent preparation, either for a social situation or for a new phase in your life. It could also signify a need to gather resources or support before engaging with others.

Overall, this dream might be encouraging you to reflect on your current social life and consider reaching out to old friends or addressing any lingering feelings from your past. Think about what aspects of your past you might want to revisit or how you can better prepare yourself for current social situations.