I am playing online and sometime people just disappear and I basically lost three times to no opponent... Obviously I should have done a little progression but I was just staying slightly ahead so as not to risk going behind and then they swung it round on the last hand.
Oh the last one I was well ahead but was trying to increase the lead (in case they came back) which failed but then was behind after the penultimate hand. So basically ended up almost the same by not wanting to risk going behind but ended up too close and losing.
When folks disappear, there are generally rules for how they will bet and play their hands while absent. Knowing the first is a huge advantage and you should bet accordingly. Options for when you are ahead are Correlate their (known) bet Play a progression to improve your position or obtain a lock if you can If you are behind: bet the opposite or play a progression in order to catch up. Knowing how the hand will be played can increase the value of your correlated bet, especially if the rule is that they will stand on their first two cards.
Increasing your lead has value if you can cross some critical thresholds (e.g. 1/2 max bet ahead, full max bet ahead, etc.), however there is no reason to ever give up the low when ahead of an absent player, unless you are ahead by less than a minimum bet. If you got swung by an absent player, then you were just extremely unlucky.