I can definitely imagine Severus doing something stupid like having an affair because he was afraid to love. If he could equate what he felt with Remus as just sex like with a prostitute or make him forget about love, then he'd feel safe from loving.
It's sad Remus was hurt, but it made Severus finally admit how he felt. Lucky for him it wasn't too late like with Lily. Unfortunately Severus almost fell back into his old habits, but finally found courage to embrace love and know where he truly belonged.
I'm happy Severus grew from such bad mistake, maybe he'll appreciate Remus more :)