Buddhism and Losing Determination

This answer might strike a little but pardon me for that in advance. I will try to give one of my friend's experience who went through same .

Currently you are feeling like... "It's more of a temporary emotion dragging me down, a kind of hopelessness or shame or maybe even self-hatred"

Considering feeling("what's the point ,it's all futile anyways") makes you truly detached from everything at that time. To know whether it's a detached feeling ,check if you feel satisfied by spiritual meditation of ,'Anaapaana' during those temporary emotions/feelings i.e. ....

Yes ,then it's detachment

It's not a temporary emotion but beginning of something else.
1.) If you have no responsibilities :: It's better to become a full time truth-seeker ,time has come to meditate deeply to get rid of Ignorance because nothing can satisfy you other than spiritual path.

2.) If you have responsibilities ,i.e. few are dependent upon you ::
Stand in front of Mirror & Smash it behind that thick skull that , "I have responsibilities left and there are few (remember the relation) Lives who would become living-Dead without me". If this is the right time , I would have been free from any responsibility. Start meditation at point when that emotion arise and declare that to be a hinderance of life like monkey thoughts of lust , Laziness etc. Wait for right time to come and when that time(of no responsibility) comes , be a full-time truth-seeker.

No it's not a detachment

Then it's called as laziness(प्रमाद) in mind.It can be due to a previous shock_of_life or due to too_much_comfortness in life. In this case ,it's Better to do a monitored meditation retreat for around 1-2 months & do some free-service (सेवा) before returning back to usual life .It will re-track you in right direction.

That friend of mine is waiting for right time and has already started his spiritual journey partially. Actually ,he is waiting for permission of parents i.e. he wants his parents to remain happy while he seeks for truth.

For those who practice, illusions disappear. One becomes...disillusioned.

sn12.23: Truly knowing and seeing is a vital condition for disillusionment.

Without illusion, craving and aversion fade away, leading to dispassion.

sn12.23: Disillusionment is a vital condition for dispassion.

And with dispassion, there is freedom for right actions, etc.

sn12.23: Dispassion is a vital condition for freedom.

And then perhaps one might encounter:

sn12.23: Freedom is a vital condition for the knowledge of ending.

So if you're struggling with disillusionment, put it to good use. Help someone with their life, clean up something that is dirty, listen to someone who feels ignored. Extend metta, compassion, rejoicing and inclusive equanimity to all you meet without illusions.

This emotion doesn't always occur, but it occurs enough for me to be held back in my practice. What should I do?

If Samsara is a very very long marathon, then just remember that if the race requires trillions steps to reach the finish line, any effort you make to put 1 step forward would mean that you're 1 step closer toward the finish line. But if you don't move your foot forward at all, you will never reach the finish line.

Defeatism and pessimism are just other activities of the mind; it's the thinking mind getting sulky because it's bored and not being allowed to do what it wants to do. If you sit with it and watch it mope that thread of mental energy will (eventually) settle down and align with the practice.

What should I do?

My advice is to:

• Be mindful and guard the sense faculties
• Find a good teacher
• Do a 10 day (or longer) intensive meditation course
• Read the Sabbasava Sutta (MN 2)
• Watch Ven. Yuttadhammo's 7 Dhamma discourses on the sutta
• Listen to Ven. Bhikkhu Bodhi's comprehensive 4 Dhamma discourses on the sutta

In brief, the Sabbasava Sutta is one of the most complete suttas in the Pali Canon. It encompasses the Buddhas entire teaching. Here the Buddha teaches how one should train oneself in order to become free from the root defilements that bind us to Samsara. The sutta is divided into 7 sections and all 7 methods work for all the defilements. The defilements should be removed by: Seeing, Restraining, Using, Enduring, Avoiding, Dispelling and Developing.

Sit on the cushion. You’ve posted scores of variants on this question and still seem to be under the impression that there’s an answer out there somewhere that’s going to get things to click for you - that somehow someone will say something that will miraculously make you committed and motivated to practice. That answer simply doesn’t exist. No amount of intellectualizing, sage advice, or sutra is going to change your mind or your circumstances. Words don’t change behavior; behavior changes behavior. Suck it up and sit. It’s not going to be fun, it’s going to take monumental effort, you aren’t going to see any discernible benefit for a long time. This is what practice looks like. It’s why it’s called a discipline. Effort doesn’t come from the outside. It comes from within. You have to provide the energy to make it happen.