Your friend believes they are suffering due to past life kamma. I have never read such a belief in the Pali suttas. Further, if this belief is true, there is no way for your friend to stop suffering since the causes of the suffering are inaccessible to them since the causes occurred in a past life.
AN 3.61 refutes the (sectarian non-Buddhist) view that suffering arises from past kamma. It states:
When one falls back on what was done in the past as being essential,
monks, there is no desire, no effort [at the thought], 'This should be
done. This shouldn't be done.' When one can't pin down as a truth or
reality what should & shouldn't be done, one dwells bewildered &
In Cula-Kammavibhanga Sutta, it is not said suffering (dukkha) arises due to past kamma. It is only said that past kamma determines certain worldly conditions, such as being short-lived, long-lived, sick, healthy, ugly, beautiful, insignificant, influential, poor, rich, low-born (social status), high-born (social status), stupidity & wisdom.
In the teaching of Dependent Origination, which explains how suffering arises, the word 'kamma' does not even exist in the Pali (despite some erroneously translations including the term 'kamma-formations'). Therefore, past kamma is unrelated to Dependent Origination, which explains the ultimate cause of suffering is ignorance.
In the teaching of the Four Noble Truths, it is explained suffering arises due to craving & new becoming occurring in the here-&-now:
And this, monks, is the noble truth of the origination of stress: the
craving that makes for new becoming — accompanied by passion &
delight, relishing now here & now there — i.e., craving for
sensual pleasure, craving to be, craving not to be.
Your friend has the non-Buddhist sectarian view described in AN 3.61. Due to this wrong view, your friend has no solution to suffering & lives unprotected, as is warned in AN 3.61.