This is a jukugo word, which usually means on'yomi readings from the kanji. You haven't learned this reading for 素 yet, so here's a mnemonic to help you:
Oh wow, you look really lovely in that suit (す). Yes, I can see you through the Internet, and I have to say, that suit is just dreamy! Don't ever take it off.
I find him attractive because of his enthusiasm for helping others.