I recently met a guy who is about 6 years older than me and proclaimed he is looking for a real relationship and marriage. He talks a good game about what a great guy he is and he knows how to treat a lady, no problem with paying the bills, blah blah blah. But I truly suspect that he is gay. He says things like he's tired of giving himself to someone and having it go nowhere. He also texted me pictures of himself that I can't see any straight man having ever sent. Lastly he never talks about sex. I threw a few innuendos out there like a fisherman casting a net... Trying to give him the opportunity to come clean but he totally avoids it. Is it rude to ask him out right, before this goes any further, I have suspicions about you being gay, are you?
Frankly, nothing you've said about the guy necessarily adds up to his being gay or raises any red flags with me. You don't describe the photos, but nowadays even straight guys pose for and send out sexy pictures of themselves. Straight men can also "give of themselves" to women and wind up heartbroken. It may simply be that this guy is different from other straight guys that you've dated who may have had commitment phobia or otherwise been insensitive.
Rather than flat out asking him if he's gay you can at least get his attitudes toward the subject by casually mentioning a gay friend, talking about gay marriage or gays in the military, starting a discussion on the subject. Make it clear you have no problem with gay people [I hope you don't] because if he is gay he probably won't come out to you. A virulently homophobic man is often hiding something, which could be repressed homosexual feelings or some other feelings of inadequacy.
If all else fails you can laugh and tell him "I've never met a straight guy like you before. You're not gay, are you, ha, ha?"
You might find this post on Asking Your Boyfriend If He's Gay helpful. Good luck.