Being outside of the case, many things seem strange. Most would agree that some of FM's action have been odd. But that doesn't mean he has knowledge of MM's fate. I remember thinking SR's interview was off, or fake, but maybe she was nervous or concerned with appearances or any other innocent explanation.
LE's treatment of the case is also puzzling. They don't seem to be actively investigating it, and they seem to be guarding important clues. MM's other family members, her friends, and BR, all seem less than forthcoming.
It is hard to rule out any possibility because there are so many curious reactions from case players, mysterious actions by MM preceding the disappearance, and indicators that support each outcome. All, JMO, of course.
I lean towards the theory that Maura took her own life and the timeline of events, the words people in the know have spoken and the actions of the people involved, IMO, do nothing to discredit the suicide theory.
Maura was an avid hiker, something that seems lost on a lot of people and her favorite place in the entire world, the place she had picked for her honeymoon, was the place she went missing in, another point that seems lost on people.
Her father's first reaction when he found out Maura went missing, was one of terror (understandably so) but not because he thought a dirtbag grabbed her, it was because he believed she went to the white mountains to do personal harm to herself. This is collaborated from the lead investigator of the case, someone who didn't know fred previously.
While searching for his daughter many days in, Fred made the comment that his daughter was going to be found naked and drunk as he pointed towards the mountains, completing confusing the guy he told this too. That to me proves, that Kathleen's ex husband is not making this comment by Fred up, because he had no clue what fred was talking about. And if you are going to make up something someone said, you are going to know what you made up means.
But, IMO, what Fred was referring to was a condition of hypothermia known as paradoxical undressing. It's the last stage before someone perishes that suffers hypothermia, they get this sensation in which they feel like they are literally burning which leads them to strip themselves of their clothes and end up dying. When found, they are often mistaken for being a victim of sexual assault because their clothes have been removed from their body.
It was only when cameras were rolling and the media was paying attention that Fred introduces this dirtbag grabbing Maura theory.
IMO, this wasn't ever a sincere belief by Fred of what happened to Maura.
With the panic he displayed in the first 24 hours of her going missing, he knew, IMO, that police better find her fast, before she could do harm to herself, and after getting to the area and being there for a few days, it was already a done deal. He wasn't getting Maura back.
The messages to the public were no longer pleas to his daughter to change course, they were almost exclusively about the incompetent job the police were doing.
I've said it before, but I believe Maura did a lot of final destination actions right up to the point she disappeared. She emptied her bank account, returned her lab coat (she had just started nursing clinicals, kind of silly to be turning the coat in after the second week of clinicals) She got the forms her father requested from her earlier accident, secured them in her car after it wrecked (knowing that the car would eventually land in the hands of her father) and she either hitched a ride to closer to her final destination or she got there eventually on foot.
Had she not wrecked that Monday night, I think she was planning to use her remaining money to rent a hotel room, possibly to write out a final note to family/ boyfriend.
I think she would've been up at the crack of dawn that Tuesday morning (hadn't she wrecked) and off to a favorite location in the mountains at which time she would've drank herself to death or eventually jumped.