If you love someone because of a reason, then you may not truly love them — you love the reason. For example: if you love your wife because she’s a great cook, then what you really love is good food, not your wife. If you love your children because they carry on your legacy, then it's your legacy you love, not your children themselves.
The same applies to our relationship with Hashem. He doesn't love us because we do mitzvos or perform well. His love is not conditional on our success or failure. He simply loves us.