As most members of my family or my friends dislike playing risk or only play occasionally, I play most of my risk online, on a mobile app called RISK: Global Domination. In this version of risk, there is an option to make alliances. This is the only diplomacy component in this game apart from asking other playing to attack specific players, which isn't very useful.
Anyway, I find that generally, the easiest continents to go for online is South America or Africa, as most other players go for Australia or no continent at all and won't let you hold a continent bonus of one such as North America. However, these continents require alliances or treaties with other players so you don't get attacked from multiple places and can expand elsewhere. The biggest problem with this is that as soon as I put the smallest amount of trust in my ally, at least 60-70% of the time they back-stab me and force me into a much weaker position.
My question is: How should I deal with this problem?
Should I try not to rely on diplomacy as much, but risk having to attack multiple stronger opponents at once, or try to mitigate or prepare for these betrayals? If anyone has other suggestions please list them down below.