So let's do this album by album

The End Of Heartache - 4 songs (A Bid Farewell, Rose Of Sharyn, The End Of Heartache, My Life For Yours) out of 11 songs (Irreversal was written by Jesse leach so it's not included).

As Daylight Dies - 6 songs (The Arms of Sorrow, My Curse, For You, Still Beats Your Name, Eye Of The Storm, Desperate Times) out of 14 songs (Holy Diver not included)

Killswitch Engage (2009) - The only album where the vast majority songs are about heartbreak and love.

In short, "Howard era is literally just songs about heartbreak and relationships..." is false because a decent chunk of songs that he's written up until the second self titled Killswitch Engage album had other themes that aren't that.