There are lot of relationship based counselling sites and forums sharing tips on questions posted by love birds who are looking out for some advice on how to handle their dating/marriage etc. Here's a site which is a Q&A service on dating questions.
A seasoned "Bro" would share his view on a text or SMS conversation screenshot posted by girls indicating if "he is into you" "he's not into you or "the verdict is still out", like this one below.
Love is lot complicated and even more while a couple is going through the dating phase, it may not be the exact way of assessing a guy's feelings for a girl, but any advice for a doubtful mind is helpful enough.
Check out the site here