You bring up Clark's catch-22 problem. The secret is so important to keep, he can't just go telling it to everyone he starts dating or thinks about dating. So he has to wait until a relationship with Lois has some potential to tell her.
Yet, by not telling her, there remains a barrier to the relationship actually developing.
At any point he tells her or she finds out, she will de distraught about it. I guess there is probably one way for her to find out that would not distress her. However I think even the moment he swallows the bomb on the Prometheus-bound shuttle is to late for that. If he was going to avoid distress, he would have told her the moment he broke the bands that Baines had him in, or I guess maybe if he told Lois that he had flown them to avoid the explosion.
