IF she was already knocked up - the possibility that CK might have been the actual bio dad could be a possible reason for taking up with the Cruiser. Do you think it could be possible that signs of his alcoholism were already showing through and she decided this wouldn't be the best decision for her kid?

Just putting it out there. For the record, based upon her own actions with Suri and the complete disregard for that child's comfort and safety when it comes to paparazzi, I find it unlikely. But, it's an interesting motive.