“Is it wrong to feel obligated to pray?”
This is like asking is it wrong to feel obligated to talk to a close friend or a loved one? Would that close friend or loved one want you to be obligated to talk to him/her? Would he/she consider failure on your part to talk to him/her regularly a sign of lack of love on your part? How would you react if your close friend or loved one tell you that he/she feels obligated to talk to you? And remember God is far more loving and forgiving that even the most loving and forgiving close friend or loved one of yours.