Feelings happen only in the moment and feelings persist as a result of how well the memory of that moment lasts. Feelings also fade, strengthen or alter as more moments occur and new memories are replaced.
If there are no new moments then that feeling maintains or weakens as memory of the moment fades. For example, if you dislike someone for their hairstyle, that feeling only happens because of the moment you saw that person's appearance and this feeling remains because that moment is kept in your mind (memory). If the next day, you see the person with a different hairstyle which is more favorable, then this moment get merged with the one from yesterday and they compromise a new feeling depending on how strong the new moment is.