[I was asked to speak in Shul A Friday night. The following is basically what I said, sticking to my rule of never speaking for longer than 7 minutes (it was actually 6 minutes). The next day, I davened in Shul B, where the Rabbi said pretty much the same thing. Cool thing is, the two other people who davened at Shul A Friday night and Shul B in the morning also noticed it.]
In the middle of the parsha, there's a heated exchange between Yaakov and Rachel when she demands children and he responds angrily. It presents a bit of a difficulty for those who like to see the Avot as flawless because if Rachel did nothing wrong, then Yaakov was wrong for getting angry, and if the anger was justified, then Rachel did something wrong. Different commentators explain it in different ways.
A few verses later, Rachel trades her night with Yaakov for some flowers called dudaim. Rashi thinks they were some type of fertility flower. If that's the case, then we see Rachel, on two occasions, trying to conceive by using some type of intervention - once by demanding from Yaakov (ostensibly that he pray for her) and once by using dudaim. Yaakov's angry response was "Ha-tachat Elokim anochi asher mana mimech pri vaten?" Again, commentators offer different explanations about what 'hatachat Elokim anochi' means. 'Tachat' clearly means 'instead of' - like in 'ayin tachat ayin', and not 'underneath' (thought the Shelah says that it does mean 'underneath - Yaakov was saying that he couldn't pray for her because he was not in Eretz Yisrael at the time).
The way i explained it is that he is angry at her because she was using him as a replacement for God. We live in a culture where people sometimes look for shortcuts - amulets, brachot from tzadikim, getting mezuzot checked, segulot, etc. in order to cure all ills. Perhaps they work, and perhaps not. Certainly, though, they are not a replacement for a direct relationship with God any more than taking prescribed drugs are. But these things often pass for 'frumkeit' and religiosity. Yaakov, the 'tzadik' whose wife demanded that she pray for him, responds angrily that whatever he might be able to do, she must confront God on her own.
Indeed, when Yosef is finally born, the verse states that God heard Rachel's voice.