Is it permissible for the two fiancés to go together to perform the 'Isha prayer and then return home?

It is permissible for the suitor to look at what entices him to marry the betrothed woman. However, once he approves of her, it becomes unlawful for him to look at her thereafter. It is permissible for him to sit with her in the presence of a mahram, but private seclusion (khalwa) with her is not permissible, due to the Prophet's (peace be upon him) saying: "No man is alone with a woman but the third of them is Satan." He should not go out with her.