What’s with all the commas in Portuguese???
to separate things that would not mean the same thing if the comma was not there.
While not wrong, this is not a very common sentence structure, to be honest.
Something like this would sound a little bit more natural, in my opinion:
Somos namorados, por isso, pelo menos damos as mãos, certo?
And if you want to simplify it further (at the cost of slightly changing its meaning):
Somos namorados, logo damos as mãos, certo?
Despite the slight change of meaning (logo / therefore), it sounds more natural. But like I said, the original sentence isn’t wrong either, it’s just not a very common way to express it.