Toby never wanted to end up with Yvonne...
Let me explain.
Toby began building the house for Spencer.(presumably he was dating Yvonne at that point since it didn’t look at all complete in 6x11)
In 6x11 Toby asks Spencer to dinner.
Also in 6x11 Toby and Emily are talking and he says that he got his degree (but it didn’t help him get a promotion(or something to that effect))
In 6x18 Spencer says “I thought you wanted to go back to school”
And he replies “that was your idea because being with a cop wasn’t good enough for you”
In 6x14 Spencer says something to the effect of
“The next 3 weeks are really important to my moms campaign”
Yvonne in 6x20 “A month ago we were talking about our future”
I’m gonna do a little extrapolation.
He got his degree, was building the house for Spencer, and asked her dinner because he wanted to get back together.
(I could even extrapolate that he bought the ring for Spencer but I won’t)
Now maybe he put off the dinner because of Charlottes murder investigation. (Been there, put up with that)
Then he finds out she’s fucking Caleb. Probably like Hanna, he assumes something went on in Spain. (Right after their pregnancy scare and break up)
So he gets dragged into the “A"ntics and Yvonne gets pissed. He cares about Yvonne and loves her, so he proposes to her (figuring Spencer’s off the market)(and maybe even to make Spencer a little jealous) (Toby’s only human after all)
I also don’t believe he ever intended to leave. Spencer asked him in 7x10 if it was goodbye and he said "for now it is” I think he was taking Yvonne away from Rosewood to keep her safe. Because A is so smart he had to make it look real.
Then the crash.
He told Aria, Yvonne was in a medically induced coma and then said “basically that means she hasn’t woken up from surgery”
THAT’S NOT WHAT THAT FUCKING MEANS.
A medically induced is when the doctors PURPOSELY put and you into a coma, because otherwise your injuries would kill you. (I’m paraphrasing of course but essentially that’s what it means.)
So….the doctors tell Toby that Yvonne isn’t improving and isn’t going to improve. There’s too much damage. They tell him that if they take her out of the coma she’ll only have x amount of hours to live.
So he (and/or her family) made the decision to wake her up. And instead of waking her up and being like “hey you got 6 hours to live” he decided to marry her so she would die happily/peacefully.
Ok I know what you’re all thinking.
If everything I’m saying in the above passages is true then the 64,000 dollar question is…
Why did Toby ever bother going out with Yvonne? He planned to get back together with Spencer so why use Yvonne? That’s so un-Toby like. So why would he do it.
The answer is ridiculously simple.
In season one we see the way Jenna treats him, I’m not just talking about the NAT video where she rapes him either. She treats him like she owns him. When Spencer broke up with him in season 2 he comes back with Jenna at his side. I don’t know as I’d call any of their other breaks “break ups” per se because they didn’t really last that long.
In the last season we found out that about 3 years from present time Jenna tried to start her crap with Toby again.
Coincidentally about the time Spoby broke up.
So he needed a girlfriend, not surprising he picked (Spencer 2.0) Yvonne but she was sweet and he grew to love her in a way.
So that’s my speel.
It’s the best rationalization I can give for a horrid storyline.
Correction: the storyline was good, the execution was horrid.