it's entirely up to you whether it's unreasonable. If you want a husband who always tells the truth, the whole truth and nothing but the truth, you haven't got one, and it's your choice how you deal with it.
I would probably forgive him, but you don't have to do so just because I would. Partnerships involve both parties being as happy as possible; if he's made you unhappy, and you don't accept his excuses, then you're within your rights to leave. But whether I or anyone else would do so is irrelevant: it's your call.