Spinelli should be grateful that Maxie did not want to marry him because obviously it does not take much to turn her head. Granted she and Franco have great chemistry. And of course General Hospital could not have a movie star join the show without giving him a "love" interest, but Franco made Maxie look like a foolish young girl. In fact as the days pass I think Maxie will find that she has a lot to be embarrassed about. Not only did it take very little for her to cheat on Spinelli, but she essentially slept with Franco on a dare, all the while convincing herself that she was in control of the situation. However, Franco was the only one that really got anything out of their encounter. He was able to use someone close to Jason for his perverse mind games and get that same person to basically insist on sleeping with him, all without ever having to agree to do the Crimson shoot.
From the moment Maxie met Franco it was obvious that she was attracted to him and did not trust herself to be alone with him. And even though she didn't try very hard to resist him, his misogynistic attitude seemed to melt away any resolve she might have had. Most women would consider misogyny an unattractive quality, but then again Maxie isn't most women. With great insight and minimal effort, Franco was able to bring out vintage Maxie, the Maxie that saw any opportunity to self-destruct and took it. And whatever else Franco might be, I think he is an observer of human nature, pointing out and exploiting weaknesses, emotional or otherwise. He certainly found Maxie's Achilles' heel and was able to use that to his advantage. And I suspect he may be trying to use this same talent to expose Jason's.