Suteneko no Karute

From Shinmakoku Scanlations:

1-3: Suteneko no KaruteKaoru
Kaoru is frustrated. He's just been dumped, again. And it's all because he could never express his feelings properly. What's wrong with him? What should he do? Feeling all alone and restless, he strolls into a gay park and meets... a cat.
Youhei is a straight guy, and younger than Kaoru. But something in Kaoru moves his heart, reminding him of a cat, the feline species he's so in love with! Can he capture Kaoru's heart, the abandoned cat?

4: Sabishgaria No Koi (Love Story of the Lonesome Man)
Sweet oneshot about guy that had been dumped by his girlfriend who meets by chance another wounded heart.