All I can really say is if we're seeing evidence of controlling, jealous temper just 3 months into their relationship - I have NO problem believing he deliberately and willfully murdered her, screams or silence.
The overwhelming majority of abusive or controlling relationships form a pattern, especially in the beginning. The abusive or controlling person seeks to make the relationship as intensely close as possible. They whisk the victim off their feet. Abuse, even psychological, is usually slower to evolve. It begins as covert and insidious, with the abuser attempting to establish control over the victim. Otherwise many victims would leave the relationship early on - and the most dangerous time for a domestic violence victim to become a homicide victim is when he/she IS leaving...
Which, in turn, begs the question...had she had enough?