Georges Ernest Boulanger by Nadar.

Shot himself a few months after his mistress died, Marguerite Bonnemain which wikipedia tells us:

“ She became the lover of the French general and minister Boulanger and died in his arms in July 1891. At his request ‘A bientôt’ (‘See you soon’) was engraved on her tomb. Two months later he shot himself in front of her grave and ‘Ai-je bien pu vivre deux mois et demi sans toi?’ (‘Did I really live two and a half months without you?’) was added to the epitaph.“

Also rumoured to have frequented the infamous male brothel in Cleveland Street, London. He looks the naughty type.