Do people deserve a second (or third or fourth or 18th) chance?

As relationship always go, this is complex.

Simplified: My Ex used to just ignore me all the time when we were dating, so naturally I broke up with him. Somewhere along the line we started kind of being friends after that. Everything was great, until even as friends, sometime he’d not respond to an instant message or a text message for days… so I stopped really talking to him. I do enjoy hanging out with him as a friend. We have fun. But being ignored angers me. He has been really nice the past 3 or 4 months, and messaging me everyday saying he wants to the gym with me. I do need a workout partner, and no one else can match my schedule. SHould I give him another chance?