Maybe she's tired of it, maybe she's taking a break, maybe she's sick of "ur hot, let's do it" messages from guys, maybe she's too busy for dating, maybe she just doesn't want to date at all right now....who knows. Women drop off and come back on frequently. So whether she's on Match or not tells you pretty much nothing about the reason therefore I say it's a pointless exercise on your part...and it shows a lack of detachment, which is neither good nor bad, it just is. We don't check on people unless we still have feelings for them.
