The Abarbanel always seems to have something interesting to say on difficult parshiyos. From the Ramban down to Achronim, everyone is bothered by what the pasuk, "V'ha'ish Moshe anav me'od..." has to do with Miriam's sin of speaking against Moshe and her punishment. Abarbanel explains that the question only arises because we put the punctuation in the wrong place. The usual reading of the pesukim is,"Vayomru," Miriam and Aharon said, "Harak b'Moshe dibeir Hashem...." Did Hashem speak only to Moshe? -- end quotation marks. New topic: "VaYishma Hashem," Hashem's heard their lashon ha'ra, which is then followed by the enigmatic, "V'ha'ish Moshe anav..." Move the quotation marks, writes Abarbanel, and you have a completely different meaning. "VaYomru" -- start quotation marks -- "Harak b'Moshe...VaYishma Hashem... V'haish Moshe" -- close quotation marks. The entire contents of pesukim 11:2-3, including "V'ha'ish Moshe anav," are Miriam's words!
There are three possible reasons that Moshe might have separated from Tziporah: 1) Moshe did not reallylike her; 2) Moshe's status as a Navi precluded his having a relationship; 3) Moshe was personally disinclined to have a relationship because he felt he should dedicate himself exclusively to Hashem. Miriam's intent was to show that all three of these excuses were invalid.
1) "Ki isha kushis lakach" -- Moshe, you knew she was a kushis when you married her and had two kids. Too late to complain about that now.
2) "Harak b'Moshe... VaYishma Hashem" -- Being a Navi does not preclude having a wife; we are also Nevi'im, Hashem also listens to us, and we remain married.
3) "V'ha'ish Moshe anav me'od?" -- Are you Moshe more humble, more special, than everyone else, that you think you should behave differently than the rest of the world? (The 'hey' of 'ha'ish' is not a 'hey hayedi'ah' but rather is a 'hey' that indicates a question.)