OK. I will be very frank. I did not read your post completely. It is way too long a description for a - characterless Abhi - as you put it.
There's something called - downward spiral. It happens to everyone at some point in their lives. There is no way to stop the spiral or get off it, only wait for it to stop. That is what Abhi went through from Tilak 1.0 on. A downward spiral with circumstances - every single one of them - working against him. But all through it, he never once let go of his love for Akshara, never could let go of his belief that his feelings for her were 100% reciprocated but something was stopping her for accepting.
Sure, he made a bad decision by getting engaged to Arohi but he did it for his mom. She is his one weakness. People are known to do a lot of things for people they love. But he never professed to have any feelings for Arohi. He didn't mislead her. Did he do the right thing in backing out of the wedding at the last minute? Of course not. But it is better than knowing the truth, marrying and then putting all three of them thru another round of wringer. It's a few days of hurt / pain / society taunts Vs lifelong agony for the three of them. If you look at it from that POV, he and Akshara did the right thing.
Of course, makers added a lot of drama to it all.
But there was never at a point where his mind or heart or body (yes, I'm including the physical aspect too because it is part and parcel of a couple in love) wavered, let alone weakened. They were all owned by one person and one person only. Akshara.
Bottom line - he is not perfect. He is not your Knight in Shining Armor. He is not the modern Devdas. But he is not characterless.
He is perfectly imperfect person in love with his Akshara
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