One of those characters that is never lucky in love? I would say yes that would make the protagonist more endearing to the audience

Write for yourself and mean it.

Theses composition rules are for the mundane, that are only to please the masses for their own attention.

Creative writing (aka fiction) is meant to be CREATIVE!

Upset the conservatives and throw in a polygamist or such. And most of all have fun with it!

Controversy draws attention by itself!

Look to Heinlein, Anthony or Melissa Scott for examples of controversy... Yes I know it's sci-fi, yet it shows the type of controversy that I am referring about. Two of those authors are very well known for controversy.

You grok? 🙃

No, it will not if you're trying to produce a romance novel. There is a rule about those. They must ALWAYS have a happy ending.

Not joking at all.
No happy ending, it will not be successful.

It could, but it needs to be one of those things where the time just wasn't right, a tragedy occurred (the love interest died), or something else that would make the protagonist endearing to the reader.

Your protagonist can always have this realistic script as long as your overall plot/script overrides this with the continuing romantic frustration being a subplot.

Why not? Failures are stepping stones to success.. so make him an expert and give him more lovers ..

A love which never succeeds in its intended purpose.

What is a love failure?

No