Peter smashed an antique chair into

[Bassim]

I am wondering if my sentences are grammatically correct.

Peter smashed an antique chair into the door, for which his wife never forgave him. The chair was handed down to her after her mother's death, and had immense value for her. She planned to bequeath it to their daughter.

 

[Lynxear]

"Peter smashed an antique chair into the door, for which his wife never forgave him. The chair was handed down to her after her mother's death, and had immense value for her. She planned to bequeath it to their daughter."

The comma should be removed in the second sentence since these are not two independent clauses.

In the last sentence I would use the past perfect tense for to plan. The reason is that "had planned" indicates there was a plan in the past. However, now that is impossible because the chair is smashed.

Peter smashed an antique chair into the door, for which his wife never forgave him. The chair was handed down to her after her mother's death and had immense value for her. She had planned to bequeath it to their daughter.

 

[Tdol]

I'd use which his wife never forgave orwhich his wife never forgave him for. ​Your version is not wrong, but it sounds a bit strained to me.