Should I ride out this long sentence with my fiance?

My fiance is facing a lot of time in TN, his charge is 2nd degree attempted murder. The smallest plea offered so far has been 25 yrs, I've held him down for a year and a half without fail. His bond finally got reduced low enough that I got him out on pre-trial release and he dumps me, as soon as the money's all paid!!! When he thought he might never get out he acted so in love with me and wanted to marry me, now he says he don't want a serious relationship and he's flirting with a bunch of dumb ho's, who I guarantee won't support him or be willing to ride this out with him. I'm broken-hearted, do you think he ever really loved me? Why is he doing this, wtf is he thinking?? Should I still hold him down when he gets sentenced, or should I let him learn the hard way??? And 1 more question, do you think he'll really cop that much time??? I really hope you can help me.....