I don't want to sound overly negative, but why assume that an honest answer to those questions will make you feel better, rather than worse?

It's not an assumption; four weeks of bibliotherapy in the form of reading Feeling Good and doing the exercises has been shown in experiments to be superior to a placebo book for treating depression (75% of patients no longer qualified for DSM criteria of major depressive disorder afterwards), and the improvements were sustained at 3-month and 3-year followup.

Of course, you could then argue that the book doesn't actually make you evaluate your situation honestly and is just mindless positive thinking, but I don't think that'd be a fair assessment of the book.

The example you mention about romantic love is quite telling. Unattractive people have a much harder time finding romantic partners . And the partners they do find tend themselves to be unattractive. (The issue of physical attractiveness is of course just one example. There are many other cognitions underlying depression and anxiety which may also be rooted in solid evidence.)

Sure, but my example was "if I'm physically unattractive I'll never find romantic love" not " "if I'm physically unattractive I'll have a much harder time finding romantic love."