I've never been in a relationship, but I like to think I'm very observant when it comes to relationships. By observing other people's relationships, some bloom, some fail, I've noticed that:
- maturity matters. Observe how he/she deals with hard situations and hard people in their life. Do they follow their emotions, or do they follow God's Word? Is she/he mature enough to handle situations in a godly way? Do they just ignore the situation, become an emotional mess, or do they take responsibility for it an do something about it?
- convictions matter. Are they actively worried about their spiritual growth, about dealing with sin, and about your sin? How do they confront sin and how do they seek to grow in their weaknesses? Do they encourage you to deal with your sin? Do they point you to Jesus when you need it?
- personality matters. Do you even like being around this person? Can you imagine spending the rest of your life with this person, with their struggles and with their passions? I know many say this isn't very important, but it does have its importance. It's not fair to marry someone just because you're lonely when you don't appreciate them for who they are (leaving aside sinful attitudes of course). God created different personalities, so I think it' important to use those personalities for His glory.