Does lack of success in performing an act of worship, such as Qiyam al-Layl or congregational prayer, mean that Allah despises the servant?

Not being granted success in a certain act of worship cannot be considered a sign of Allah's wrath upon a person. If one resolves to obey but is prevented by an obstacle, a complete good deed is written for him. However, if this recurs and becomes a habit, one should review themselves and repent to Allah, because their sins might be what has hindered them from obedience, for sins are among the greatest causes of Allah's displeasure.