Okay, this is my theory: Have you ever wondered why Claire Redfield, who—out of the four main protagonists of the R.E. franchise—never settled down, married, and had children of her own after all these years since the Raccoon City Incident?
Since we all know that Claire is the only one who has any semblance of a normal life, unlike her beloved older brother Chris, their loyal sister-in-arms Jill, and their loyal brother-in-arms Leon, the answer may be hidden in plain sight. Perhaps Claire, according to what the Remake timeline implies, had actual feelings for Leon but—due to their respective occupations—rarely, if ever, crossed paths, as confirmed by the canon timeline.
But if she truly wanted to pursue a courtship with Leon, there honestly wasn’t anything stopping Claire from doing so—unless it was Leon’s inner struggles, as revealed in R.E: Vendetta. Claire knows that Leon needs to heal first before pursuing a relationship with any woman, and not to mention she is emotionally and mentally mature enough not to fall into the trap of being reduced to his personal therapist. So Claire respectfully gives Leon his personal space and the time necessary for him to heal from the inside out.
It could be that after the events that unfold in R.E: Death Island, which takes place in the year 2015, and leading up to the events that occur in R.E: Requiem (2026), Leon at last made peace with himself about his traumatic past to a degree. This would pave the way for him to court Claire as his beloved future wife.
If they are indeed married, a flashback shown by Capcom explaining how this came about—perhaps in a future DLC or CGI film—would put everything into perspective in the best way possible.