The gate ''mowt'' מט means to be moved or slip. By formation it is --from מ the marriage ט. You get the sense of someone falling away from the marriage. <ref group="v">mowt מט - slip, move, ''f.'' from מ the marriage ט.</ref>
The opposite ''tam'' טמ means to narrow or stop. It is used of closing your ears, or your lips. The reversal is in a movement away vs. the stopping of that movement. <ref group="v">tam טמ - stop, narrow.</ref>