Probably.
And I think Abraham was trying to please Sarai. And in a way, he did subordinate God's will to his desires but I think that was cause he was looking at the situation in the flesh, and not through spiritual eyes.
Just want to pass this along to you:
Someone said that back in those days having children was considered a blessing. Conversely, the inability to have children was somewhat of a disgrace, which explains why Hagar looked down on Sarai.
It was common practice for another woman to bear the child until birth (their version of artificial insemination?) so they can raise him/her as their own. Therefore it was not regarded as adultery in situations like this.
Just thought you might be interested.