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import datetime
from dateutil.relativedelta import relativedelta

your_datetime = datetime.datetime.now()
your_datetime + relativedelta(months=1) # adds one month

That function clips the overflowing day of the months:

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>>> datetime(2021, 1, 28) + relativedelta(months=1)
datetime.datetime(2021, 2, 28, 0, 0)
>>> datetime(2021, 1, 29) + relativedelta(months=1)
datetime.datetime(2021, 2, 28, 0, 0)
>>> datetime(2021, 1, 30) + relativedelta(months=1)
datetime.datetime(2021, 2, 28, 0, 0)
>>> datetime(2021, 1, 31) + relativedelta(months=1)
datetime.datetime(2021, 2, 28, 0, 0)
>>> datetime(2021, 1, 31) + relativedelta(months=2)
datetime.datetime(2021, 3, 31, 0, 0)

Intuitive solution doesn’t work

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>>> your_datetime = datetime.datetime.now()
>>> your_datetime + datetime.timedelta(months=1)
Traceback (most recent call last):
File ““, line 1, in ?
TypeError: ‘months’ is an invalid keyword argument for this function

Probably “months” are not included in the standard library because of non-obvious semantic of the overflow.