Mid and Jungle: How to manage the following situation

The situation is the following.

Suppose you are a Midlaner, who is either even or almost even of enemy midlaner. Then, imagine the following happens: your Jungler ends up being in the following spot: with 25-35% hp (more generally, in "kill range" of enemy midlaner), near bottom-enemy-side of the map, towards midlane (in particular, much closer to enemy midlaner than you), spotted by enemy wards and running away from a 90-100% hp enemy jungler or support (suppose a support able to kill your Jungler quickly, say Pyke). Finally, assume that either you and enemy midlaner have more or less equal mobility, or that enemy midlaner is a bit more mobile than you. The important point is that there is no way for you to get to your Jungler before enemy midlaner gets to him.

Finally, assume that Toplane (both yours and enemy) is a non-factor (e.g., they are both dead or are just afk farming and cant TP) and also that your botlane is a non-factor.

Now, the scenario runs like this:

1. Your Jungler spam-pings help, while he tries to run away, but his positioning is playing against him;
2. The "chaser" enemy (jungler or support) is slightly faster/has a slow and starts closing the gap;
3. Enemy midlaner arrives there first (we basically assumed that this was inevitable);

If nothing is done, what would happen is: 4. Enemy midlaner and enemy chaser quickly kill him; 5. Your Jungler flames you for "gg mid no help blind r3t4## ff 15".

The main question of the topic is: what is the optimal strategy to take as a midlaner?

I think that the answer to this question heavily depends upon the following factor: the 2v2 (Mid+Jungle) potential. Let's discuss two possible options: Strategy A: No Help. You decide not to help your Jungler. You try to take another advantage, such as: free farming, pushing lane, etc... Strategy B: Help. You decide to go help him.

Now, the situation explained above basically reads that the 2v2 is heavily against you. Since enemy midlaner arrives first, there is little you can do to save your Jungler. Unless the enemies both heavily misplay, he is doomed. Should you still try to save him, thereby risking that the enemy team gets a double kill, but betting on the odds that it turns out good?

As stated, this is a somewhat simplified problem, since it does not explicitly take into account HP, mana, CDs, Flash, champion kits, etc. But it boils down to the following: should you help your Jungler when you "know" (i.e., when you make a prediction) that the 2v2 will most likely result in a double kill for the enemy team?

Recently, some situations which could be compared to the above (but in reality much more complicated) happened to me and I got hard-flamed by the Jungler due to choosing not to help (but this is another point entirely). In that moment, the "honest but harsh" thinking was that your ally was dead and you could only make the situation worse by trying to help him. By the way, this comes from someone who typically dies when trying to help an ally, so...

Looking forward to your comments on the matter.

P.S. This refers to a SoloQ scenario (you are not Duo with anyone), not to coordinated play where you and your Jungler are in vocal chat.