Are the Cubans likely to create serious problems (other than questioning you with their habitual curiosity) for attempting to enter the country every 2-6 weeks for 4-8 days as a tourist?


Well, they will, eventually get curious. Just tell them you have a girlfriend and all will be well.

They will certainly be curious, as they should be. Immigration of evey country in the world would be curious.
Whether or not it is a problem depends upon what you are doing. Once they decide to find out they will probably discover what you are doing.
If you are working as a mula, or criticizing the system in an indiscrete fashion, that would be enough to create serious problems. If you are meeting a few different girls every trip, that would also be a problem, eventually. If you are visiting the same girl friend every time, and acting respectfully, you probbly won't have any problem.
Assume that they know everything and act accordingly.

Depending on what your activities are, you probably will have no concerns. However, if you are involved in illegal actions, or indiscrete relations, the problems created will probably eventually effect you, but undoubtedly will effect those you associate, and LIVE in Cuba more.

They will ask, you'll find a nice excuse and that's it. I would not tell them there is a girlfriend involved.

jeje.... that's what I always told them (one gf, that is) and they would smile, male or female officer, and let me pass.