I echo comments from karlshammer, plus suin and miryam; in our situation one of us has a phD and is qualified to practice their profession in three global jurisdictions; the other did not complete high school. The evidence provided to support the genuineness of your relationship is far more important than if either of you is more or less academically qualified. Yes an IO uses discretion, but if you provide evidence which when viewed by stranger shows cohabitation (where required), development of relationship, legal union documents and supporting photographs etc, there is not much room for an IO to say that when taking all of that into account, the education gap is a deal breaker.