Few people would argue against Corbyn being a principled fighter. From his youth as a supporter of peace, to his deliberations with groups others would call 'terrorists', Corbyn has proven he has his beliefs and is willing to stick up for his convictions. Sadly though, that same strength could well end up being his downfall.
We know that his politics are left-leaning. That's OK! He has many supporters. We know he is a peaceful person avoiding strife, but his unwillingness, for example, to come out and outright condemn anti-Semitism is undoubtedly hurting him.
We also know that deep down, Corbyn is a Brexiteer. Again he would not be alone, and has learned enough about politics to keep his mouth shut rather than sell out his own beliefs. With the vote coming up in parliament, if Corbyn sells out Labour, and supports May thereby enabling her to get the legislation past the Commons, it will cost him dearly. The first rule of the opposition is to get into power.
With his own party being principally against Brexit, his unwillingness to take a a more firm stand on Brexit, is weakening his own party. As things stand, if he was to support fully another referendum, he would have Lib-Dems, Greens, SNP and enough votes virtually to force another election. One he can win, as long as he doesn't try to implement Brexit. It is radioactive and it will destroy him. His only chance is to take the final decision (which must include an option to back out of Brexit) to the people. If May was to do this, she would have an excellent chance of getting through to the next election.
You've done all the hard work Jeremy, don't blow it now.