Surprised? No.
In all honesty, little in this world surprises me.
I say this all the time at my job, and I think it applies here: there is always hope, and there are never any guarantees.
Heath and Michelle's relationship is between the two of them, I have only my impressions from the media; they certainly would not have been, nor will they likely be the last, couple to make a go of it for a baby.
I have never heard nor seen anything to make me believe/suspect Heath felt he needed to 'prove' his sexuality to the world.