We don't know a lot about Sollux and Feferi's relationship (which is a crying shame if you ask me, because I think they have a very cute dynamic), so anything to do with them you're going to have to take with a grain of salt.

That being said, I feel like that's not only an oversimplification of both Aradia and Feferi (they're more than just "happy-go-lucky gals with long wavy hair"), but also "dating a girl because she reminds you of your ex hours after she exploded" feels a bit disrespectful in a way that I don't think Sollux would go for. He's an asshole, sure, but he's not an Asshole™, you feel me?

Besides, there's a good chance Sollux wasn't even the one to ask her out in the first place.

SOLLUX: you are 2o riidiiculou2ly optiimii2tiic iit'2 kiind of 2iickeniing, why do you even put up wiith me?
SOLLUX: iif you weren't 2o great ii would thiink you were a fuckiing iidiiot for liikiing me.

Sollux doesn't let himself have nice things. Sollux's self-loathing levels are rivalled only by Karkat Fucking Vantas. Even if he wanted to ask her out, I highly doubt he'd bring himself to "trouble her" like that. I think it's much more likely that Feferi, the extroverted life player, was the one to break that particular ice.

I really wish we'd gotten more about their relationship in particular... they could have been called Goldfish............