Why did Arthur Huntington marry Helen?

Just finished Tenant of Wildfell Hall and loved it! I actually got super teary a few times when reading Helen's diary :( there was so much darkness and perversion, it was crazy. The scene where Grimsley is trying to tempt Lord Lowborough to challenge Huntington to a duel really struck me. He must have known Arthur would have killed him, and he encouraged it anyways (whether or not Arthur knew what he was up to). I think that Grimsley was actually the devil among them, he seemed to always be at the elbow of his friends whenever they were about to take their next big leap into vice or sin.

But one of my biggest questions is why did Arthur marry Helen in the first place? As much as he professed love and affection, I don't know why he would be attracted to her enough to even consider marriage! Did he ever atctually intend to marry her, or did he come up with a proposal on the spot when her Aunt caught them to avoid scandal? Maybe he hoped her guardians would say no and he could have the satisfaction of conquering her heart and affection without the commitment?