Much work on the processing of filler-gap dependencies shows that comprehenders actively commit to gap positions. This process is suppressed in syntactic island contexts, suggesting that grammatical principles constrain active gap formation. However, filler-gap dependencies may also exceptionally resolve with a resumptive pronoun in islands. Resumption is ungrammatical in English, but immediately facilitates processing (Hofmeister & Norcliffe, 2013). This implies that comprehenders can actively pursue ungrammatical dependencies, contradicting the previous established generalization. In this paper, I argue for a mechanistic account of resumption in comprehension that helps resolve this paradox. In my proposal, upon encountering a filler, comprehenders commit to memory a representation of an expected gap (or gapped predicate). However, the comprehender may fail to maintain this representation over time, due to decay of the representation over time, or due to strain on working memory while processing complex syntactic constructions, e.g., island configurations. When the expectation of the gap is lost, then a pronoun may help the comprehender recover the intended interpretation through a regular coreference relation. To demonstrate this, I show four speeded acceptability judgment tasks. In Experiment 1, comprehenders rated short resumptive dependencies as ungrammatical. In Experiment 2, longer resumptive dependencies were rated more acceptable. In Experiments 3 and 4, I showed that externally straining working memory by the addition of a word-list memorization task increased the acceptability of ungrammatical sentences overall, including resumptive sentences in Experiment 4. This establishes that increased processing difficulty results in higher acceptance of ungrammatical filler dependencies, which I argue underlies the facilitatory effect of resumption in real-time processing.