Complex sentence: Biographers of Owen disagree over whether or not this relationship was sexual--certainly, coded sonnets by Scott Moncrieff, addressed to a "Mr W.O.," suggest that his professed love for Owen was unrequited.
Split into simpler sentences: Biographers of Owen disagree over whether or not this relationship was sexual. Coded sonnets by Scott Moncrieff, addressed to a "Mr W.O.," suggest that his love for Owen was unrequited.