Can men fall in love with characters in novels? Of course they can.
Men and women fall in love with fictional characters of all kind. Think of the teen girl pining after a boy group, or the teen boy pining after a Playboy centerfold. Both are "in love" with – that is, they feel romantic and sexual interest for – a fiction. Because, of course, those media images are not real people, but a fiction created exactly for that purpose: that teen girls and boys fall in love with them.
There is some gender bias in what kind of fictitious character men and women fall in love with, with men preferring visual depictions of sexy women and women preferring narrative deptictions of strong, successful, and able men. Because of that preferrence, men fall in love more with characters in visual media, while women are more susceptible to literary characters (Shades of Grey) and celebrities (such as movie and music stars).
But not all men (nor women) are the same, and just as there are women who consume visual pornography, there are men who like to read, and some of them fall in love with characters in novels. I am an example of those.
During puberty, I very much wanted a girlfriend, but did not have the courage to approach any girl. I was so afraid of being rejected, that my default type of "relationship" became pining for girls from afar. I spent long afternoons imagining stories of how I would get to know and then interact with the girl I had a crush on. Those were stories similar to what I read: adventure stories, mostly, in the vein of Edith Blyton's Famous Five. In my daydreaming, I was the boy with the dangerous secret, and somehow that secret got me together with the girl – although my imangination never managed to go that far.
When I was around fourteen or fifteen, I began to read the novels of C. J. Cherryh. If you are familiar with the work of that author you will know that her early novels are full of some subliminal erotic or romantic tension that never leads to any kind of relationship and is in fact never named by the author or voiced by her characters. Then, in the Morgaine cycle, it becomes the overt structure of the narrative: the male protagonist falls in love with the elf-like warrior woman who forces him to serve as her knight. At first he serves her, because he must, but later, after she would have set him free, he continues to serve her out of love. A love that she does not feel and does not answer.
That relationship was such an exact image of what I felt for the girls in my life, that I fell in love with Morgaine, the female lead of the novels. And with her author, in turn. At that time I knew nothing about C. J. Cherryh, except that her name indicated a woman. I had never read an interview with her or seen a photograph of her. But I felt for her something of what I felt through her writing. Eventually I wrote a letter to her – that was before email, so I wrote on paper and by hand –, and actually received a very kind and friendly reply (which, although I didn't voice my feelings and she didn't address them, healed me of my crush – probably because her answer made me realize that she was actually a person apart from myself).
I still have the Morgaine novels in my shelf, but haven't read them in about thirty years. Today, I find the kind of relationship they depict self-abusive and prefer women who are approachable, both by being physically present and through their open behaviour. Nevertheless, when I look at those books, I still feel an echo of my past desire.
I have also had vague crushes on almost every female protagonist or love interest in all the books I have read. In fact, I would go so far as to say that any man who reads erotic or romantic stories, feels something erotic or romantic for the female characters in those novels. If he didn't feel sexual desire or romantic interest for those characters, he wouldn't read that kind of book. Because that is the purpose of reading fiction: to experience what the protagonists experience.