Good mental compatiblity, not sexual compatibility, will keep a Gem Venus around. That's the key. Gem Venus needs lots and lots of mental stimulation, and not just occasionally. I'm a Gem Venus, and yes I do get bored with people very quickly. I don't cheat, but I am very restless. I don't like unimaginative people who settle for the ordinary and routine. I'm very curious, always thinking and need to explore things mentality. If I'm around someone who represses that Gem nature of mine, I won't stay around for long.
People accuse us Gem Venusians of unfaithfulness, but we're only doing what is proper for our nature. If you bore us, we're gone. And many Gem Venusian feel like I do - hey, it's not my fault someone's boring, so don't blame me!
It's would be good to remember that Mars contacts with Venus is mainly sexual compatibility, and in itself does not promise a lasting relationship, so I wouldn't go looking for a long term relationship that way anyhow. Besides, good contacts with Mercury and Venus are very critical for a Gem Venusian in synastry - those are the planets that rule the mind (Venus corules the emotional, intuitive side of the brain with mercury). Mars contacts matter less for us, because that's a physical planet. So don't think that you're going to hook a Gem Venusian with your Gem Mars alone. Me personally, I often find Gem Martians physically attractive, but they're not always interesting enough for me in the more cerebral ways to make me seriously consider them as a romatic prospect. (Oh yeah, we Gem Vensuians are extremely fickle too - LOL)