I feel like with Bruce/Selina, it's often Bruce who (ffs!!) needs to compromise his fascist, rigid vigilantism. (And also get over those trust/intimacy issues) And Selina who has to compromise her solitary lifestyle. (Also cut down on that whole stealing thing)
Thing with Selina and Bruce is that Selina still does *bad* things: she steals. Is Bruce a boy scout like Clark? Hellz to the no. He isn't above using torture methods to obtain information. However, because she steals, this reflects on her honesty/integrity and therein, I think, lies the trust issues.
Also Bruce has got that fear of becoming one of them -- the "freaks." If by giving in to Selina is he okaying crime when he's so anti-crime? (Of course by this point, you could also argue by keeping the Joker alive, he's okaying murder. Buuuuuuut that's another argument for another day!!)