All this is quite normal. It often happens that people have great ideas, insights and revelations on e that melt like snow in the sun when returning to daily life. Jotting things down on paper is another good one. It does not have to be an essay, just a few lines written from your heart to jog your memory about the ideas and feelings. Sketching or painting may be even a better way, since it is more creative.
Fingerpaint is lovely.
If a few of you share this, you can support each other later in remembering what your heart was really telling you. This could be helpful in the case of your friend. However, it does not mean that suddenly he will feel different. He may need help in getting through his darkest feelings around the death of his friend, either with the help of friends or even with a counsellor. Reading books by people in the same situation can also be useful.