The speaker compares his heart to a front gate, overgrown with black ivy and kept shut. The reason is given plainly: it has been closed "since I found my wife." The line is ambiguous. It could mean he found her, as in met her, or that he found her out, perhaps in some betrayal. The poem doesn't say, and that gap leaves a quiet unease. Either way, something changed, and the gate hasn't opened since.
The last two lines turn the image around. The speaker says he lets the gate "go to him / that shall hire my house," as if he is giving up the whole property, and perhaps the marriage or the life attached to it, to whoever comes next. The tone is flat and weary rather than angry. The ivy suggests neglect and slow decay, and the word "black" darkens it further. Together these details create a mood of resignation: a man who has stopped guarding what he once kept, because he no longer feels it is his.