Is what a girl does by way of acts of obedience after her engagement, which she had been doing before that seeking God's pleasure, considered hypocrisy if she feels that she is now doing them for the sake of her fiancé?

It is impermissible for a suitor and his fiancée to be alone together because he is a stranger to her before the marriage contract, and Satan is the third between them. As for showing off (riyaa'), it is more subtle than the creeping of an ant. A Muslim must strive to achieve sincerity in his actions and supplicate with the mentioned prayer: "O Allah, we seek refuge in You from associating anything with You knowingly, and we seek Your forgiveness for what we do not know."