I have narrowed it down to two scenarios that I believe could have happened it in fact MB is guilty:
...
2) This was a rage killing. He murdered her, cleaned up, and disposed of the body leaving evidence in his cottage.
*****And I find this unlikely because they held him for almost the full 96 hours THEN charged him with murder.
I don't find the delay surprising because:
1) The police have to present their evidence to the CPS before charges can be brought, and the CPS need time to evaluate that evidence. Although not unprecedented, a murder charge without a body is unusual and they would need convincing that the evidence really is watertight before agreeing to proceed in such circumstances.
2) The police will have been aware that they cannot question the suspect further after charges have been brought, unless new evidence comes to light. They will therefore have wanted to use the maximum time allowed by law to persuade him to reveal the location of the body before bringing charges.