A comma

[Bassim]

I wonder if my use of a comma in these sentences is correct.

1.Their relationship was nearing the end, which unfortunately, neither of them could have anticipated at that time.
2. The hotel room had a splendid view over the castle, built in the 14th century, and which nowadays functioned as a residence of a rich banker.
3. The oldest player in the team, who in his legs had hundreds of matches, had finally decided to retire.
4. The soldier hit him hard in the face, making him unconscious.
5. The river, which before never flooded, is now bursting its banks.

[Bennevis]

1.Their relationship was nearing the end, which, unfortunately, neither of them could have anticipated at that time.
2. The hotel room had a splendid view over the castle, built in the 14th century, and which nowadays functioned as a residence of a rich banker.
3. The oldest player on the team, who in his legs had hundreds of matches, had finally decided to retire.
4. The soldier hit him hard in the face, making him unconscious.
5. The river, which before never flooded, is now bursting its banks.

[Bassim]

Dear Bennevis,
Thank you for helping me and correcting my mistakes.

[CarloSsS]

3. The oldest player on the team, who in his legs had hundreds of matches, had finally decided to retire.

Not a teacher.
Just FYI:"In the/a team" is also a correct use of the phrase. It's just mostly used in BrE, whereas "On the/a team" is an AmE expression.