she is at wit's end and I am one of the few persons, Bob takes advice from, I feel obligated to help her and him

Listening to your advice is an additional advantage that his girlfriend may have lost already. However, if you mention that you talked to her about their household problems he may see that as a back-stab or side-picking and you may lose that advantage.

You could mention your last encounter with her and describe how she seemed sad, or exhausted, or exasperated, or [other descriptive adjective] in order to make him realize that his help is really needed to alleviate her burden.

If he mentions again that you or her are pressuring him, you can let him see the whole picture: "a woman taking care of an household by herself, another adult (food/clothes), and a baby without being rewarded the entire time will eventually deplete her entire energy. It seems to me like a dead-end to any relationship, but that's your call to make".

You could also focus some questions on her son, in order to understand how much interaction he has with him and to point out that at this age (4 y.o.) he requires a lot of attention, not just for food and hygiene but for playtime as well. You could mention that it can be surprisingly fun to play with them and help them in various tasks and they will remember that for a lifetime.

she is at wit's end and I am one of the few persons, Bob takes advice from, I feel obligated to help her and him

Listening to your advice is an additional advantage that his girlfriend may have lost already. However, if you mention that you talked to her about their household problems he may see that as a back-stab or side-picking and you may lose that advantage.

You could mention your last encounter with her and describe how she seemed sad, or exhausted, or exasperated, or [other descriptive adjective] in order to make him realize that his help is really needed to alleviate her burden.

If he mentions again that you or her are pressuring him, you can let him see the whole picture: "a woman taking care of an household by herself, another adult (food/clothes), and a baby without being rewarded the entire time will eventually deplete her entire energy. It seems to me like a dead-end to any relationship, but that's your call to make".

You could also focus some questions on her son, in order to understand how much interaction he has with him and to point out that at this age (4 y.o.) he requires a lot of attention, not just for food and hygiene but for playtime as well. Example: "it can be surprisingly fun to play with kids this age, or even helping them out in various tasks, they will remember you for a lifetime... They will also never forget about you if you decide to ignore them (blaming you for their screwed up childhood when they grow up)."