As noted, fortified wines last rather well after opening. 6 weeks is not excessive for an ordinary tawny, ruby or LBV port, madeira or a sherry. (Vintage ports should really be drunk more quickly - see below re fine wines)
Wines will keep better longer when refrigerated.
Vacu-vins are iffy. They are inexpensive and work that way, tending to lose vacuum daily. But they are certainly better than leaving the bottle unopened on the counter and after the second glass a bit better than merely corking the bottle.
My view is the better the wine, the less it lasts. A fine complex Sauternes has many more fine nuances than say an Oz dessert Muscat. As you would expect, you lose the finer, more delicate features first. The wine is still drinkable after a week, but it will be not the same experience you had on the first night.
That said, there really is no reason why you alone could not drink your wine in 10 days. From Friday to second Monday, you have six weekend meals. But if you don't.... you can tell us how long the wine lasted.