I mean no disrespect, but I'm not buying it. Besides, it wasn't a weekend--it was a weekday. I think she loved her boyfriend too and was hurt when he cheated on her. Like I said, I'm having a hard time connecting the crashing of her dad's car and a sudden decision to run off with a lover. In truth, I think she had personal demons which have nothing to do with secret lovers or boyfriends. I know I could be wrong, but it seems like an easy answer to say she ran off with a guy. It's a classic answer, but often not true, especially when she hasn't turned up anywhere since. I'm more inclined to think she ran into someone new after her accident in NH and started a new life.
There is absolutely no evidence she had a secret lover. In fact, why would she need to keep it a secret? She was single. Her boyfriend didn't even live in the area. The male secret lover was the one who needed to keep it secret if he was married---not her. Besides, usually a friend of one of them catches on, so it isn't that much of a secret (people witness the secret lover hanging around Maura at her jobs or they see him enter her dorm room, etc.). In other words, someone usually has an idea that they were getting close, especially when she turns up missing! Wouldn't they talk to police about their suspicions??
I also find it too complex. I think the answer to what happened to her is simpler. The secret lover is an added element with no evidence to back it up. It's junk, IMO. I could be wrong, but with no evidence to support this scenario, I have to cross it off the list for now.
JMO