It is not that easy to give a simple answer.
There are many "arenas" in life, and each one of them has a different consequence for withholding or not our feelings.
In love?
well, the consequence can be devastating, sometimes we keep to ourselves feelings for others, and eventually we suffer, because we never let out what we feel.
In a society?
Witholding feelings of anger, injustice or revenge can lead to different scenarios.
Sometimes WE MUST withold what we feel in order to keep from hurting someone, or because sometimes we must exercise PRUDENCE, and tolerance to others.
But in the end, we can WITHOLD telling, yelling, asking, claiming, talking..etc, and each scenario, and cirncunstance can be as diferent as a fingerprint.
But DENYING our feelings to ourselves, or WITHOLDING our feelings to ourselves, I think in general the consequence can be to kill our own soul.
as much as we STRENGTH ourselves and withold our feelings (when most of the times we do it so IT DOES NOT HURT ) We are also closing the door the good feelings.
Bad and Good feelings enter and leave trought the same door:
our heart.
hope is useful.