... Keep in mind, this relationship will eventually fail, if he does not overcome his anxieties ...
Who are you to say that? Why do you dismiss the possibility that the OP and her Significant Other may carry on together indefinitely, albeit with areas of continuing difficulty in their relationship?
If the OP and her other half (or any other couple, for that matter) decide to see a counsellor or therapist together, IMHO a fundamental screening question to the intended therapist is "How do you handle it if you decide that it's best for a couple that they should separate, how do you broach it with them?" To which there is only one acceptable answer: "It's not for me to suggest that a couple should separate, that can only be their decision".
... and team up with you to work through problems.
I think that INTPs hearing of a desire to "team up" to "deal with" a problem would hear it as a take-over bid i.e. "I want to take charge of the problem-solving process, I have an agenda and a prescription for what I will offer towards resolution (chosen by me based on my perception of what I think your needs are, relatively easy for me to do, and not too disagreeable to me) and a prescription for what you need to do (chosen by me to meet my needs, would be easy for me if I were you, so should be easy for you and if it isn't well you need to work on it)".
In fairness, this sort of response may be triggered more with an xSxx partner, and I may be speaking from my baggage (ESFJ mother with undedeveloped Secondary -
http://www.personalitypage.com/html/ESFJ_per.html - "Potential Problem Areas, 11 bullet points), but still I think INTPs would generally be suspicious of "teaming up" to deal with a couple problem. The Ti thought process would go along the lines: "yes, we can be a team dealing with an *external* problem, but this is about *us*, so if we 'team up' then the 'team' will be 'working on' one or the other of us, and it doesn't sound as if my partner has in mind that it'll be her, so I'm the problem, I'm being invited to give away my independence of thought and action and be subsumed into a 'team' to 'deal with' *me* - no thanks!
Just say no to what you don't want
I understand the OP's problem to be that she isn't getting what she does want, not that she's getting what she doesn't want - a "sin" of omission, rather than commission, on the part of her other half.
To OP - I've been intending to post more generally but I feel (yes, feel) that there's a piece of the jigsaw missing, that my Ti process isn't being 'fed' fully. I think it may be *how* your other half's heart was broken - did his underdeveloped xxFx mean that he was controlled, manipulated, toyed with, dismissed? Did he make the same mistake (rephrase: 'find himself in the same relationship situation') again and again? Did he learn or is it shut down? Or work in progress?
One general-purpose thought is that if he feeds his Ti with reading on 'theory of relationship' then it might help him feel more comfortable that T-type theory of relationship does actually exist and that relationship is not just all about the 'foreign land' of xxFx. As I'm an INTP myself, it won't be any surprise to you to hear that I'm not talking Mars-and-Venus or Barbara deAngelis; that material does have its place, and yes, its dignity, but it is basically all xSxJ prescription, there is no underlying structure, no deep or pattern-recognising conceptualisation, to it. I would suggest Schnarch to an INTP - googlebooks has some of his material. He's a bit full of himself in recounting his case studies and success stories, but that doesn't detract from his theory. Perhaps his best-known is the (mis-titled) "Passionate Marriage" - it should have been titled "Impassioned Marriage". Sorry to be so INTP about that, but I felt forced to make the point .....