Therapy is very frustrating, i agree with you. Progress is soooo slow, and there seems to be this barrier i simply cannot break through. But at least it helped with some of my most self-destructive impulses like my addiction to fentanyl painkillers, which is the reason i keep going there,
I am a bit of an outlier i think, because i have been in multiple relationships for the last 27 years (it's not that i had the courage to actually try for relationships, but it still happened, back then when i had a bit of social life in my early 20s), so i at least wasn't physically lonely (in the beginning), but emotionally i always withdrew after the "honeymoon" phase, trapping myself in a limbo where i lived with someone, but i couldn't do shit because i wasn't able to take the space for myself i would've needed to actually live, or even end the relationship out of fear of conflict.
I am actually going to live on my own for the first time now (starting with april or may), and I think it will be for the better. I do fear the loneliness, but it will probably beat being stuck in perpetuity in a long dead relationship.
It really is a lonely disorder, even when there are people.