Complex sentence: Malcolm believes that Anna may be contemplating a romance with a coworker who keeps coming around the house; although this elicits sadness, rather than anger, he repeatedly has difficulty opening the door to his basement office.
Split into simpler sentences: Malcolm believes that Anna may be contemplating a romance with a coworker who keeps coming around the house, although this elicits sadness, rather than anger, from him. Malcolm also repeatedly has difficulty opening the door to his basement office.