When you say "love" route, do you just mean any sexual scenes? in that case I would say corruption will be faster. If you say love as in actual loving relationship, then the seduction route will probably reach that sooner.
The way I see it going for her: in corruption you get sexual scenes that she consents to but she really isn't very interested in for a while, then she slowly over time realizes she like doing those things and likes the MC
and in the seduction route I think she will witness MC being a generally good guy, and slowly fall out of love with her current man (Aden I think his name is), and starts falling for MC, this will probably happen after Steph accepts the harem situation and the MC starts being openly romantic with other women.
Its really hard to say, though