판다스를 이용했다고 볼 수는 없는데, 어쨌든 쭉 한번 보세요.

>>> import pandas as pd
>>> from itertools import combinations


>>> df = pd.DataFrame({ "id":[1,1,1,2,2,3,3,3], "title":list("ABCDEFGH") })
>>> df
   id title
0   1     A
1   1     B
2   1     C
3   2     D
4   2     E
5   3     F
6   3     G
7   3     H


>>> df[df["id"] == 1]["title"]
0    A
1    B
2    C
Name: title, dtype: object


>>> list(combinations(df[df["id"]==1]["title"], 2))
[('A', 'B'), ('A', 'C'), ('B', 'C')]


>>> for _id in df["id"].unique():
    print(_id)


1
2
3
>>> for _id in df["id"].unique():
    for pair in combinations(df[df["id"]==_id]["title"], 2):
        print(_id, pair)


1 ('A', 'B')
1 ('A', 'C')
1 ('B', 'C')
2 ('D', 'E')
3 ('F', 'G')
3 ('F', 'H')
3 ('G', 'H')
>>> data = []
>>> for _id in df["id"].unique():
    for pair in combinations(df[df["id"]==_id]["title"], 2):
        data.append({ "id":_id, "title_1":pair[0], "title_2":pair[1] })


>>> df2 = pd.DataFrame(data)
>>> df2
   id title_1 title_2
0   1       A       B
1   1       A       C
2   1       B       C
3   2       D       E
4   3       F       G
5   3       F       H
6   3       G       H