Will Blackpill Blessing allow you to find someone else, or does it jade you from believing you can?
You will be able to find someone else and forget the other girl, if you maxx your stats successfully.
Thus, it will not NECESSARILY jade you, but it will change your sub-job class from "Bluepilled Cuck" to "Blackpilled Incel", which you can further upgrade later in the game.
Your abilities will change too, from
"Attempt simping Lvl 10", "Morph into WhiteKnight Lvl 5" & "Propose love Lvl 2"
to
"Looksmaxx Lvl 1", "Detect IOI's Lvl 1" & "Flex Lvl 1".
At later job classes you may attain the abiility "Pump and dump lvl 1" and some more, but it takes dedication or pay to win. Depending on your character, pay to win may be the only option.
The new job will however also include a "Frustration meter", which can have different effects, depending on the amount of "Frustratin points" and losses you have.
All in all it's a two-edged sword. You may or may not be able to profit from the job change. If your Frustration meter goes too high, you DO get jaded, but depending on the circumstances, you can recover and keep improving your stats.
But at the end of the day, it depends heavily on your character base stats, what you put points into, and how you use the job abilities.
In some cases, there have been players who have not been able to improve their job class even with pay to win, but it's not clear if those characters will never be able to upgrade. After all, new patches are being made every now and then a.k.a circumstances in the game may change over time.
Regardless of whether you can make use of the new job class, the Blackpill Blessing is nearly always an upgrade. I would always recommend it for your character, unless he has very maxxed out stats at the very beginning, in which case it doesn't make much of a difference whether you receive the Blessing or not.